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# Any Arithmetic Tutors here? Seriously.

Della

**I''m almost innumerate. I can add and subtract. I know long division.%0D\
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But I don''t "get" fractions, percentages or algebra.%0D\
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If you help me, I promise to show my work.%0D\
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Della

- Okay Della, where do you want to start?
- Do you cook?
- Do you need this knowledge for your work?\ \ Or is this a lame-o attempt to plug the gaping holes in your education?
- I love math. What do you need to know dear? I can help up until we get to Calculus :)
- Get a goddamned blog.
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I get that. But, let''s say I''m shopping. I see a shirt that''s already on sale at $38.50 with an additional 30% off.%0D\
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I don''t know how to figure out the cost of the shirt.%0D\
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Della, Happy Easter

- Can you calculate 10%? Do that and multiply by 3.
- "I get that. But, let''s say I''m shopping. I see a shirt that''s already on sale at $38.50 with an additional 30% off."\ \ Really easy.\ \ 10% of 38.50 is 3.85 (so far so good)\ \ 3.85 + 3.85 is 7.70\ \ 7.70 + 3.85 is 11.55\ \ even easier--$3.85 is pretty close to $4--so the shirt''s add''l 30% off is around $12.\ \ The nuns were good for something.
- Do you mean 10% divided into 38.50?%0D\
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10)38.50 %0D\
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ten goes into 38.50 3 times.%0D\
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which = 30, leaving 8.50%0D\
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10 cannot go into 8.50%0D\
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It''s here where I stare down at my desk, hoping teacher won''t "check" my work%0D\
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Della

- Della, hon, you''ve got mathlexia.
- At first glance I thought this was headlined Arithmetic Tumors.
- Me too, r11, LOL!
- Ok, I''ll come clean. %0D\
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I''m an on-call sub teacher grades K thru 8. I''m rarely called in. One day, however, I had 4th graders. My instructions were to hand out a math review for them.%0D\
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One little girl got stuck on a problem with fractions. She asked me to help her find the answer.%0D\
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I could not help her. I felt terrible.%0D\
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Fortunately, within a few minutes, another teacher was due to come in and assist the class with math, as he regularly does even when the regular teacher is teaching. %0D\
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As a child, I fell in love with letters. I took to them immediately and never cheated on them with numbers. In my defense, I grew up in an era (60''s and 70''s) when the methods of teaching math are different from today.%0D\
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I even bought a basic Arithmetic soft-cover book, hoping to teach myself, but I see those symbols and close the book.%0D\
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Della

- Ten Percent can easily be calculated by this trick:\ \ Move the decimal point ONE position to the left.\ \ Example:\ \ 38.50 move the decimal = 3.85\ \ 57.99 move the decimal = 5.79\ \ 12.75 move the decimal = 1.27
- 10 cannot go into 8.50\ \ Correct. So then the question is: how much of ten can go into the 8.50? Or, what percentage of ten can go into 8.50?\ \ Move the decimal to the right (to calculate TEN PERCENT) and you''ll see that it is .85. \ \ .85 is just another way of writing 85%.
- Let''s see what TWENTY percent of 8.50 is?\ \ First calculate TEN percent.\ \ Ten percent of 8.50 is .85.\ \ Then DOUBLE THAT to get twenty percent.\ \ .85 plus .85 = 1.70\ \ Just start practicing this in your every day life. A good place to practice this is at restaurants when calculating the tip.
- Calculating Tips:\ \ Let''s say your final bill (at the Olive Garden) is 36.91.\ \ Move the decimal = 3.69.\ \ Double that to get twenty percent.\ \ It''s easier to round up to 3.70 and double that.\ \ 3.70 plus 3.70 = 7.40.\ \ That''s a twenty percent tip! \ \ (Hey, they gave free refills.)
- One is the loneliest number.%0D\
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This is all you need to know.
Buy a calculator, hon.

- Congratulations, Della -- you're even worse than I am (which I didn't think possible). But I cook & usually have to divide or increase recipes -- I also shop sales -- so I get lots of practice with fractions. It is easier to use decimal points (.75 instead of 3/4) & I always calculate 10% or 5% or 1%, then multiply or divide that. 15% off of $18.88: 10% of $18.88 is $1.88 (move the decimal one place to the left) -- 5% is half of 10%, so divide $1.88 by 2 = $.94 -- 15% is 5% times 3, so multiply $.94 by 3 = $2.82 -- so the discount is $2.82, & subtract that from $18.88 to get the sale price of $16.04. Or round $18.88 off to $20.00 & it's quicker (though less precise): 10% of $20 is $2, divided by 2 is $1 (5%), times 3 is $3 (15%), so the discount is roughly $3 & the sale price is roughly $17. You get 1% by moving the decimal two places to the left -- 1% of $5.00 is $.05. Then you can multiply the 1% by 3 to get 3%, etc. There's a 3% rebate on gas at Costco -- for $4.07 per gallon, 1% is $.04 so 3% is $.12, so I'm paying $4.07 minus $.12, or $3.95 (which is cheaper than $3.99 at U-Pump). I spend a lot of time standing in the aisle counting on my fingers, but so what? We all have our own talents & strengths.
- When calculating 15% off $18.88, why not calculate 10% by moving the decimal point, divide it by two to get the figure for 5%, then simply add them together to get 15%? That''s easier than multiplying the figure for 5% by three.
- Arthritic tumors.
- I something''s 30% off that means you''re only paying 70% of the price, right? Easiest thing to do is multiply the price by 0.7. \ \ 38.5 x 0.7 = 26.95\ \ One step, done.
- Shop at Kmart - they put signs that do it for you on top of the clothing racks.
- For laughs, try tutoring someone who has no concept of negative numbers.
- R8 & R14 are good teachers Della - try what they''re shown you.\ \ If you want to figure out what 30% off is, take the price, $38.50 and move the decimal point, just one place to the left. That gives you $3.85 which is 10%.\ \ Then add $3.85 + $3.85 + 3.85 = $11.55.\ \ Here''s another way to do it. If $3.85 is 10%, as in the example above, round it up to 4 and multiply by 3. In other words, you take your 10% and multiply it by 3 to get the 30%. Then subtract that from the ticket price. It will a little high of an estimate, but not by much.\ \ Does this help?
- I don''t think it is any easier, R20 -- & I didn''t want to confuse Della. But your method does work too, of course.\
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With fractions, it''s all a matter of concept. You''ve got to picture a pie & cut it into equal sections -- 15% of the pie is either a tenth of the pie cut in half plus another one-tenth piece, or a fifth of the pie plus two more one-fifth pieces. Either method gives you as much pie, but one may fill your plate more quickly & easily than the other.
R19

- R19/26, I think you mean to say a twentieth of the pie plus two more one-twentieth pieces.
R20

- Don''t feel bad, OP. I didn''t understand fractions or decimals until I took mechanical drawing in high school. There was something about seeing fractions on a ruler that made it click for me.%0D\ %0D
- I love Della.
- 1 Silver Dollar\
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physically break it in half gives you\
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2 Half Dollars\
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physically break those in half gives you\
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4 Quarters of a Dollar\
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physically break those in have gives you\
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12.5 cents. 8 Pieces of a Dollar (pieces of eight)\
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2 of those pieces = 1 quarter (2 bits)
Early American money using Spanish Silver Dollars

- Just remember that there are 16 and 2/3 decimal half pennies in a shilling.
- Back at ya'' r29.%0D\
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ALL of this helps. Thank you so much. I will repeatedly re-read this thread and practice what I read.%0D\
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I want to fall in love with numbers and I so envy people who love them. Recently, I had a conversation with someone who went so far as to say that , to her, math explains the world.%0D\
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I was entranced by that and I want to know what that''s like.%0D\
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Thanks again, everybody.%0D
Della

- Well that''s a different thing altogether, Della.\ \ You know what it''s like to fall in love with words -- so do I -- I don''t think it''s possible for people like us to fall in love with numbers too. Or vice versa.\ \ Best we can do is try to make numbers work for us in a pinch -- which I assume is what the numbers people are doing with words. No spark, just one in front of the other -- like walking instead of dancing.
- Fractions
http://www.khanacademy.org/search?page_search_query=fractions

- algebra
- Della, \ \ You might have dyscalculia. Read about it at the link I am providing and then think about getting tested if you think you should. \ \ I can only post the one link. But Louisiana State University has scads of online classes for University credit. And the few non credit (remedial) classes that they offer up online deal with really basic math. You might want to look into trying your hand at some of those classes because they do have a Professor behind them and all of that. \ \ have a nice day, \ \ "mildly drunk on Easter Lesbian"
- [quote] 10 cannot go into 8.50\ \ With lube and relaxation it can.
- It''s usually easier if you round the numbers up or down. $38.50 is pretty close to $40. 30% off means you pay 70%. 70% of $40 is $28. So you pay a little less than $28 ($26.95, as described above).
- [quote]I get that. But, let''s say I''m shopping. I see a shirt that''s already on sale at $38.50 with an additional 30% off.\ \ 1) Take your cell phone out of your pocket and use its calculator.\ \ 2) Enter 38.5 x .3\ \ 3) The result is how much the discount is. Subtract that from $38.50 to find the price you pay.\ \ Or, for fewer keystrokes, instead of calculating the price of the discount, calculate the price you''ll pay.\ \ 1) Take your cell phone out of your pocket and use its calculator.\ \ 2) Enter 38.5 x .7\ \ Instead of figuring the amount of the 30% discount, you''ve calculated the 70% you''ll have to pay.
- R36.%0D\
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thank you. thank you. thank you. thank you. thank you.%0D\
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What a valuable website. I recognize my childhood self in the "The Discalculia Syndrome" by Renee M. Newmann.%0D\
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What a relief. %0D\
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Della

- Della, \
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If it''s $38.50 and you get 30% off it''s easy. \
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Break it down. \
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10% means move the decimal one place to the right. So $38.50 becomes $3.850\
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Multiply $3.850 times 3 = $11.55 off. \
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To really simplify, round $3.850 to $4 times 3 = $12 which is only $0.45 difference between the more accurate method above.
LuciferTheLightBringer

- Thanks Lucifer. You haved lived up to your DL name.%0D\
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You meant to write "...one place to the left."%0D\
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Right? %0D\
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I love ALL of you DL math lovers/tutors.
Della

- Della I could''ve started this thread. I can add and subtract and do some long division. That''s about it. I''m your same age, too.%0D\ %0D\ %0D\ I can barely retain a number pattern in my head and try to memorize the best I can. Is it a learning disabilty of some sort?
- [quote]Is it a learning disabilty of some sort?%0D\ %0D\ %0D\ According to some of the posters in this thread, it can be. Do you read OK?
- r43, click on the link at r36. Scroll down the left until you get to the link by Leslie Newmann. %0D\
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It''s along article but perhaps, like me, you will recognize yourself.%0D\
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I know now after reading that, we''re numerous. "numerous"-Get it?%0D\
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Della

- 2+2=5.
Datalounge Math

- You know, I''m already having a shitty day and feeling bad, did you really have to be an asshole R44? I didn''t read the whole thread before I posted.
R43

- Thanks R36/Della.%0D\ %0D\ lol...I guess we are numerous.%0D
- Honestly, I strongly suggest you work on multiplication tables. Memorize them. You probably know most of them already, but practice any you don't know immediately, or any you have to stop and think about.%0D %0D As for fractions, they're pretty straight forward, honestly. They're a way of representing a "part" of something. The numerator (top or left of the fraction line) tells you how many parts, and the denominator (the bottom or right of the fraction line) tell you "out of how many".%0D %0D So 2/3 is two parts out of three, or two thirds.%0D %0D Now, to add fractions, you have to have the same denominator. You can't add 1/3 and 1/4 together directly. The way you get the same denominator is by multiplying each term by 1. Well, that doesn't sound very useful, does it? Everything times 1 is just itself, right? Well, with fractions you can represent the "1" in any number of ways... 4/4 is 1. 3/3 is 1. Right?%0D %0D So to add 1/3 and 1/4, you first find the least common multiple (LCM). For 3 and 4, that's 12. So multiple each side by a representation of 1 such that the denominator is 12. So multiple 1/3 by 4/4, and multiple 1/4 by 3/3. This gives you 4/12 + 3/12. Now just add the numerators like normal: 4+3 = 7.%0D %0D So the answer to "what is one-third plus one-fourth" is "seven twelths", or 7/12.%0D %0D Any time you want to add or subtract fractions, you must find the least common multiple.%0D %0D
- whoa,r49.%0D\
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I''ve re-read your post about five times. And guess what? I think I''m "getting" it.%0D\
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Do any two numbers share a LCM?
Della

- The easiest solution is to only shop when things are 50% off.
Ciaran

- I can fart ten times in a row. Does that make me a math tooter?
- That would make you a tweeter R52. A perfect tweet that was!
- [quote]Do any two numbers share a LCM?%0D %0D Yes, any two numbers have a least common multiple.%0D %0D In the worst case, it's just the two numbers multipled together (like 3 and 4).%0D %0D In some cases, it's a smaller number than that. But if you don't want to be complicated, you can just multiply each side by the other side's denominator. It's essentially the same thing... 1/2 + 1/5, for example: Multiple 1/2 by 5/5, and 1/5 by 2/2... this gives you 5/10 + 2/10 = 7/10. It's just that easy.%0D %0D So don't let "Least common multiples" freak you out. Think of it like this: multiples of 5 are 5, 10, 15, 20, 25, 30, etc. Multiples of 4 are 4, 8, 12, 16, 20, 24, 28, etc. You just take the number and multiply it by 1, 2, 3, 4, etc). The "least common multiple" is the smallest number that is the same in both lists. In this case, it's 20.%0D %0D If you have 1/2 plus 1/4 though, the least common multiple is 4. Of course, everything still works if you use 8 (2 * 4), becuase you're just multiplying by one. So lets' see how that works.%0D %0D 1/2 + 1/4 ... using LCM, you multiply 1/2 by 2/2 and get 2/4 + 1/4 = 3/4. And there you have your answer.%0D %0D Now, let's just ignoer the LCM and multiply the denominators together to get 8. So multiply the 1/2 by 4/4 to get 4/8, and multiply the 1/4 by 2/2 to get 2/8. Now you get 4/8 + 2/8 = 6/8. %0D %0D Note that 6/8 doesn't look the same as 3/4, but they are in fact the same. You can see this by dividing a circle into 8ths, and then coloring in 6 of of them, and you'll see that three quarters of the circle is filled.%0D %0D So what you have to do here is "simplify the fraction". Any time you have a fraction where the numberator and the denominator share a common factor, you can "reduce" the faction, or simplify it. In this case, both the 6 and the 8 are divisible by 2. (2 times 3 = 6, and 2 times 4 = 8).%0D %0D So you can divide the numberator and the denominator by 2, and you end up with 3/4.%0D %0D The "2" in this case is called the Greatest Common Factor. If you list out the factors of the numberator and denominator, it's the largest one that is common to both. %0D %0D It is NOT the case that any two numbers have a Greatest Common Factor (or really, for many number-pairs, the greatest common factor is '1', which is basically a way of saying you can't simplify fractions with those two numbers).%0D %0D So 3/7 cannot be reduced or simplified, because the Greatest Common Factor is 1.%0D %0D But 16/24 can be reduced because they have a Greatest Common Factor of 8. Divide both the top and the bottom by 8 and you get 2/3.%0D %0D I hope this isn't too much all at once.%0D
- This is a good book: [italic]Innumeracy: Mathematical Illiteracy and Its Consequences [/italic] by John Allen Paulos%0D\
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Now, there is one caveat: the author is kind of an elitist dick, and gets condescending at times, and it''s sometimes annoying enough to make it hard to keep reading. But the content is otherwise really, really good.%0D\
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Being innumerate makes you vunerable to a lot of specious arguments (advertising, and things like republican political lies). The more innumerate you are, the more gullible you are, because you can be so easily bamboozled by numbers.%0D\
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It''s worth checking out. It''s not very long, and it''s not really heavy on mathematics, it''s more talking ABOUT innumeracy, not about math itself.%0D
http://www.amazon.com/Innumeracy-Mathematical-Illiteracy-Its-Consequences/dp/0809058405

- Think of it this way Della, Mathematics is the Queen of the Sciences precisely because She is not a science, She is a symbolic language Art, developed by Man, to try to understand the world around us. For devout people it is also an attempt to understand the mind of God.\ \ So, in a very real way, Mathematics describes the same beauty of the world just in symbols that aren''t an alphabet.
- [quote]You know what it''s like to fall in love with words -- so do I -- I don''t think it''s possible for people like us to fall in love with numbers too. Or vice versa.\ \ That''s not true at all. I love them both.
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I wish a teacher had told the class the exact words you used in your post. I truly believe, as a result, that my aversion to arithmetic would have been greatly reduced. %0D\
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I am a naturally bright and curious human being, and those words, heard when I was a child, would have made total sense to me. Why? Because I already used letters in that same way you describe.%0D\
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Let there be no perception that I blame my childhood teachers. Teachers are a foundational block of society and deserve much more respect and money then they receive.%0D\
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I''m just glad that the methods of teaching math nowadays seem a bit more user-friendly then when I was a child.
Della

- Sweetums, have you heard of a calculator? A lot of those newfangled smart phones even have an app for that.
- I always tell my math-phobic liberal arts friends to approach math as language, and understand there is a sociology in the relationships of numbers.\ \ "of" means "multiply by"\ \ "off" means subtract.\ \ Look at the units of a word problem -- if the train is going 90 miles per ("per" means divide) hour and they need to know how far the train has traveled in 87 minutes, you know the train travels 90 miles in 60 minutes, or 1.5 miles per minute, so in 87 minutes, it will travel:\ \ 1.5 miles/minute x 87 minutes = 130.5 miles
- This book is a bit astray from the original topic of arithmetic, but speaks to the appreciation of mathematics. It written by someone who was not a mathematician and puts the development of mathematics in a historical context with lay explanations. That said, it delves into some seriously advanced topics.\
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Mathematics: From the Birth of Numbers. Jan Gullberg.
http://www.amazon.com/Mathematics-Birth-Numbers-Jan-Gullberg/dp/039304002X

- R54's post gave me a head ache. No offense. I just have an aversion to math. Taking from a previous post, it really does feel like a language I simply do not understand.%0D %0D I had problems with it from early on, even had a private math tutor for a year. Failed geometry, of all things, in HS and had to go to summer school. I think I just never understood the basics and that has hindered me from getting the rest of it fully.%0D %0D The same was true with chemistry. My HS teacher was from Argentina or something. She was not a very good teacher to begin with and her accent was incomprehensible to me. %0D %0D I always did very well in physics, biology, anatomy and a bit of a science geek. Chemistry was completely lost on me, so I avoided it.%0D %0D I recently had to take a science overview pre-req. Of course, chemisty was involved. I dreaded it. However, the professor was excellent and I, by this time, was older and could wrestle with topics on my own. I finally got it and realized that it wasn't all that complex to begin with.
- You really can''t do phyiscs without math, so I''m curious how you managed to do well in physics without liking math?%0D\ %0D\ And math IS a language. The thing is, most of the math that most people learn is just the drugery of learning the alphabet and some basic grammar. The vast majority of people never actually learn the expressiveness of the language itself (calculus and beyond).%0D\ %0D\ Addition, subtraction, multiplication, and division is like learning your ABCs. Algebra is like learning some basic spelling rules.%0D\ %0D\ There''s so much more to math than that, and like any language, you can only get good at it with lots of practice and immersion.%0D\ %0D
- Della,%0D %0D I have been in your place. And the easiest thing to do is have the kids work in pairs. Then they can ask each other for help. %0D %0D If that is not possible I used the old trick of okay, let's look at the problem. If you're having it, maybe others are. Then I write it on the board. Then I ask the class who wants to try this one. There is always some hands that would shoot straight up for the smart, do gooder kids. Let him come up and do the problem. Things should start coming back to you. If you still don't know if it's right. As the class do we all agree with Bobby's answer. If majority say yes move on, if say no and Megan's hand goes straight up and she wants to fix it, let her do so. %0D %0D This way you don't look like an idiot and you can get through.%0D %0D Or if you don't have time to do all of that, just say circle the ones you don't understand and we will do them all together. Then you run out of time, and just shout save those to go over with your permanent teacher. %0D %0D Then go over your math.%0D %0D
- You sound like you''re an excellent teacher, r64. Your students are fortunate.%0D\
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"I used the old trick of okay, let''s look at the problem. If you''re having it, maybe others are." %0D\
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I love that because it doesn''t make the child feel like they alone can''t figure it out and , meanwhile, everybody else has. And, um, of course, little does the child know that I can''t figure it out either.%0D\
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Or...can they? %0D\
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Speaking of the language of math teaching. It just occurred to me that, as a child, math consisted of solving "problems." Well, who wants to confront "problems?"%0D\
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"puzzles" or "riddles" would have been far more enticing then hearing teacher say the dreaded. "OK, everybody. Take out your math PROBLEMS."
Della

- If it''s any comfort to you Della R58, those are the exact words of my favorite Math professor in college. I also never heard them in elementary school. That''s what finally got me curious enough to try to figure out what he meant by that. Then I was able to step back and look at patterns and at math problems as whole "things," that were connected to other whole "things."
R56

- Yeah, they're not math "problems"... they're "questions" to which you need to find the answers.%0D %0D You're definitely solving little puzzles.%0D %0D It's especially true of algebra... the question is "what is the value of X?" And "X" is usually something you WANT to find out... how tall is the building, how fast was the car going, how far did the train travel, how heavy was the weight...%0D %0D These are things I deal with every day. I know it's a common joke that people never use alegebra... but I do every day. Not just in my job, but when shopping. When you're comparing the prices of two things, you need to make sure you're comparing apples to apples. If one item is more expensive than the other... are you getting more? When there's a sale, how much are you REALLY saving? Is that advertisement making something soung good when it's really not?%0D %0D With math, you can avoid being taken advantage of. You can be a smarter consumer. You can save money and find better deals. Sometimes a "sale" price on an item is STILL more expensive per-unit (like per-ounce) than just buying the regular non-sale priced item in the larger size.%0D %0D Numbers are all around you, all around everyone, all the time.%0D
- "Numbers are all around you, all around everyone, all the time."%0D\
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Yes, r67, and I''m going to befriend them.%0D\
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Della

- Any more questions?%0D
- Not right now, r69. I''m still digesting what''s here so far. %0D\
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Btw, the information here inspired me to look up two baseball terms that I constantly hear in the summer and have always been curious about: "earned run average" and "batting average."%0D\
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I''ll just say that, in reading about those two terms, I got a bit ahead of my current skills
Della

- Anyone?
- Batting average. When a batter faces a pitcher and either gets on base, scores, or gets out, that is an "at bat." The batting average says if you look at all his at bats, that is the percent of times he got on base or scored by hitting the ball. If he got on base by a walk or hit by a pitch or the catcher dropped the ball, it doesn't count as a hit but it is an at bat. If he hit the ball but it went foul or was caught or he was thrown out, it is not a hit but it is an at bat. It is unusual for someone to "hit" more than once in every three times (batting average higher than .333) he comes to bat because so much can happen at the plate. But that's not math, that's sports dyslexia, and frankly unbelievable from you della, since you follow sports so closely. So you if you want to know batting average for a game, you have to know how many times the batter came up to face the pitcher. There is a complication though that if the hitter bunts or pops up in order to advance an on-base runner even though he himself will be out, and it works, then the scorer, if convinced that's what happened, will not count that as an "at bat" because it helped the team and shouldn't be used to reduce his batting average.In addition if a batter gets a hit but only gets on base because a fielder chose to throw someone else out instead of him, then even though the batter got on base it is not considered a hit and kept off the batting average even though the at bat is counted. So he got on base but his batting average actually declined because it did not help the team since a base runner in a more advanced position was called out. This is called "Fielder's Choice."%0D %0D Earned run average says for all the games the pitcher pitched, how many times did the opponents score off him (excluding scores caused by errors by the fielding team) on average for each game? But then it gets complicated, because pitchers don't always work a full game and sometimes the game runs extra innings. So to calculate the ERA, they decided not to calculate the earned runs per game but per total innings pitched divided by 9. (Of course since pitchers don't always work full innings either, so they could have changed it to at bats, but for whatever reason they didn't).
- [quote]You really can't do phyiscs without math You can't DO it, but some schools teach conceptual physics, which describes the various laws and phenomena, so people can understand what is going on without necessarily feeling the need to calculate it through. For example, E= mc^2 All that says is that energy is dependent on a mass of an object and how fast it is going. Europeans came up with that centuries before -- E = mv^2. Einstein just decided that it could apply to the mass of molecules going at the speed of light. So now, we can see through a light spectrum the molecular make up of various objects such as water or planets based on the color of the lights (which are electromagnetic radiation) they emit by nature. The Japanese radiation we've lately been concerned about is energy radiating from the various substances used in the reactors. The important thing to know is that the reactors got the stuff to radiate, then the shields broke, and now the radiating stuff is blowing around, not the radiation itself. Some of the stuff will radiate for a few weeks, the rest is the problem -- once you get it started (like lighting a fire) it will continue radiating for hundreds of years and nothing will stop it. It's a good deal when contained and used for power. It is deadly when blowing around, which is what we have now. So the other result of E=mc^2 was also the realization that if you get certain substances going, you could release enough energy to melt New Mexican sand into glass, and destroy entire Japanese cities. Why is the question people who understand can now ask -- how is left to the people who delve into the calculations and DO the physics.
- I can''t figure out decimals. like .01 = ?%0D\ %0D\ .001 is ? .0001 is ?.%0D\ %0D\ Or John beat bill by 5 one hundreths of a second looks like what? .005? %0D\ %0D\ Also, if 1 out of one hundred is 1% then 1 out of ten is ?%0D\ %0D\ I honestly can''t see patterns and numbers and it''s caused me a great deal of anxiety and shame throughout my life. I''ve gone to great lengths to hide it.%0D\ %0D\ I can''t tell you how many times I''ve wanted to help out at fundraisers or concession stands or garages sales but can''t because I''m afraid I won''t be able to figure out how much change to give back.
- I''d love to comfort you, r74, but I''m struggling myself, but, seriously, re-reading the posts here has helped. Maybe because I''m relaxed. %0D\
%0D\
I''m good at making change because I know how to subtract. I''ve got some studying to do on percent and fractions.%0D\
%0D\
I''m so sorry you feel anxiety and shame.
Della

- [quote]For example, E= mc^2 ... All that says is that energy is dependent on a mass of an object and how fast it is going.%0D\ %0D\ It says nothing of the sort. You''re completely wrong, in fact.%0D\ %0D\ What E = mc^2 says is that energy and mass are the same thing... you can convert one to the other. Since "c" is the speed of light, and that''s VERY fast, you can get a LOT of energy out of a very little mass. This is the basis of the atom bomb.%0D\ %0D\ It''s not talking about potential energy or kinetic energy... it''s about conversion of mass to energy, and conversion of energy to mass.%0D\ %0D\ Your other equation is close to the equation for momentum: p=mv ... momentum equals mass times velocity. %0D\ %0D\ Now, F=mv^2 is force (contact force) equals mass times velocity squared.%0D\ %0D\ Though it looks similar to E=mc^2, it means something very, very different.%0D\ %0D\ I''m really hoping the rest of your post is a parody.%0D\ %0D
- R74, just think about decimal places. To the left of the decimal point, we're all pretty used to it. The ones place, the tens place, the hundreds place, the thousands place:%0D %0D 1%0D %0D 10%0D %0D 100%0D %0D etc.%0D %0D Now, the right of the decimal place just goes the same, but it's 1/10, 1/100, 1/100:%0D %0D .1%0D %0D .01%0D %0D .001%0D %0D So just like the number 23 is "2 tens plus 3 ones", the number .23 is "2 1/10ths plus 3 1/100ths".%0D %0D So .1 = 1/10. %0D %0D It's also easy to remember that moving the decimal one place to the right is multiplying by ten (2.30 times ten is 23.0). %0D %0D Moving the decimal point the other way is dividing by ten (23.0 divided by ten is 2.3).%0D %0D Leading and trailing zeros can always be added or dropped.%0D %0D You can do the math yourself. 1 divided by 10 is 0.1 ... 0.1 times 10 is 1. %0D %0D So, to answer you requestion:%0D %0D [quote]Or John beat bill by 5 one hundreths of a second looks like what?%0D %0D 0.05%0D %0D [quote]Also, if 1 out of one hundred is 1% then 1 out of ten is ?%0D %0D One out of one hundred = 1/100 = 1% = 0.01%0D %0D One out of ten = 1/10 = 10% = 0.1%0D %0D One out of one = 1/1 = 100% = 1%0D %0D
- There is so much amazing and (relatively) easy to understand knowledge in this thread. %0D\ Thank you to all of you who''ve been explaining things to our dear, beloved Della, and to everyone. %0D\ My head is spinning reading all this information but I think I wish I could have studied math via the DL back when I was a kid and I would have had a better understanding of it. %0D\ I''d have rather bene called a "c-nt" by some random DLer than a "total loser" to my face by a teacher.
- Average = "add up all the numbers, and then divide by the total count of number"%0D\ %0D\ So if the high temperature for each of three consecutive days was 50, 56, and 60, then what was the average high temperature for those days? Well, you add 57 + 51 + 60 = 168, and then divide that total by 3 = 56.%0D\ %0D\ The average is sometimes called the "mean".%0D\ %0D\ The median is the middle number, when you put all the numbers in order from lowest to highest. So the median of the above list of high emperature is (putting the numbers in order from low to high: 51, 57, 60): 57. No math involved! :-) When there is an even number of numbers, you average the two numbers in the middle.%0D\ %0D\ %0D\ %0D
- This site might be helpful for some who want to look around more on their own: "Math is Fun"
- Great link at R80.
- Afternoon tutoring bump
- Evening tutoring bump%0D
- I''m guessing nobody likes to do math on a Sunday...%0D
- In higher math, you get to guess solutions
- Okay, I have another question. How can I tell which is the better percentage? %0D\ %0D\ Example: Jim hit the ball 8 times out of 36 times at bat. Bob has hit it 19 times at 89 times at bat. %0D\ %0D\ %0D\ BTW, thank to all of you who have contributed. I really do appreciate it.
- Well, if you have a calculator, you can just divide the numerators by the denominators, and see which number is bigger:%0D %0D Jim = 8/36 = .2222%0D %0D Bob = 19/89 = .2135%0D %0D So Jim has the better percentage.%0D %0D If you are trying to it in your own head, when they're this close, with those fractions, it would be pretty difficult even for someone with a good head for math. But in general, you can simplify and estimate. %0D %0D For example, 8/36 can be simplified and reduced... both numerator and denominator are divisible by 2, giving you 4/18. Still divisible by 2, you get 2/9. Now, for Bob, 19 is prime, and 89 isn't evenly divisible by 19, so... estimate by saying it's sorta close to 20/90. Which also gives you 2/9ths if you simplify. Now, since you had to estimate by inflating the number just a bit, you can still come to the conclusion that Jim had the better average, but like I said, it's not always blindingly obvious.%0D %0D It's sometimes good to memorize some basic fraction/decimal equivalents. All the "nineths" are easy:%0D %0D 1/9 = .1111...%0D %0D 2/9 = .2222...%0D %0D 3/9 = .3333...%0D %0D on up to 8/9 = .8888.... and 9/9 is, of course, 1.%0D %0D The 1/4ths are also easy: .25, .5, .75, and 1%0D %0D The 1/5ths are also easy, just count by twos: 0.2, 0.4, 0.6, 0.8, and 1.0%0D %0D I hope that helps a little.%0D %0D %0D %0D
- I don''t know if it helped the OP but it did me.
- It''s weird, I''m actually quite good at the more complicated math like algebra, calculus, LCM [which we called Lowest Common Denominator], etc... and yet I have trouble with percentages!\
\
For example, I can easily: multiply two 5-digit numbers in my head; plot a 3D graph [x, y, z]; add/subtract/multiply/divide any fractions with any other fractions; calculate 5a x 6b [= 30ab]; and even calculate something like [5 to the 3rd power + 3 to the 2nd power] + 6 x [8 + 3] [= 200]..\
\
.. but yet I have trouble calculating, say 45% of $68!\
\
So I''m pretty sure I don''t have discalculia, just a minor aberration in my brainpan?\
\
Of course, I do have a way of roughly calculating percentages which helps me cope: in the example 45% of $68, I know that half [50%] of 68 is 32, so I figure 45% is about $28-ish.\
\
But it''d be nice to be completely accurate without needing a calculator!
CC

- Delia,\ \ Actually, giving change is a matter of addition. Start with the amount of the purchase - say $12.25. The customer gives you a $20. You add 3 quarters to make $13. $2 dollars to make $15. $5 dollars make $20. I have a small retail store, and it is surprising how hard a concept this is to teach to young people I hire,
- I remember we were taught to count out change in 4th grade. I remember it very distinctly.%0D\ %0D
- I am a professional with an advanced degree and my lack of math skills causes me great anxiety and shame. Thank you DL.
Sir Duncen Capalot

- R92, feel free to ask questions.%0D
- Midweek bump
- Thursday is math day... surely there are more questions?
- R87 took too long. If you look at 8/36 you notice that 8*4 is 32 and 8*5 is 40, so 8/36 is midway between one fourth and one fifth.%0D\ 19*2=38. 38*2=76. So 19*4 is 76 and 19*5 is 76+19=95. So since 89 is closer to 95 than it is to 76, Bob''s percentage is closer to one-fifth than one-fourth, which means Jim does better.
- R96, I was trying to keep it simple (emphasis on being able to follow, rather than emphasis on speed)%0D
- 19 and 89 are both masturbatory numbers - they can only be entered by 1 and themselves. So lonely.\
\
8 and 36 are even numbers and can get a lot more action with other numbers - they''re more whorish.\
\
8/36 wins.
Homo math

- W&W for R98!
- I equate the teaching of math in schools with sexual assault.
- Any more math tutors needed?
- Numbers are my friends. Numbers are my friends.
Della

- Puncuation in grammar = symbols in arithmetic.
Della

- Any more tutoring required?
Willing and able to help out

- Any more math tutoring desired?
Bump!

- I''m getting it. Thank you, all DL posters.%0D\
%0D\
The Chicago Cubs; to you Dad, I see your faithfullness. Now, however, I''m watching the Brewers against the Arizona Diamondbacks.%0D\
%0D\
Numbers are my friends. Numbers are my friends.%0D\
%0D\
Serious.
Della, seeing what the catcher sees....

- Bump
Della

- Why is the catcher so devalued? Numbers and knees have to be the cruelest combination.
Della

- Those who know the game understand that the catcher is in charge.
- I had to brush up on my math skills last year; this site was a valuable resource:
- Math in Action:\ \ Using math to do things
- All respect to you, r109. Brewers will lose tonight.%0D\
%0D\
Damn. MLB catchers are busted up to. the. max.
Della

- Just put a dollar sign in front of everything, and suddenly math becomes a breeze.
- Go to YouTube (seriously) and enter a search for Kahn Academy. Select the basics. \ \ You''re welcome.
- This thread makes me want to do an 8 ball.
- I use the calculator on my cell phone.
- Use the calculator on your phone. \ \ move the decimal point to figure 10%. \ \ 10% of $38 is $3.8\ \ Multiply 3.8 x 3 to determine 30%\ \ 3.8 x 3 = 11.4\ \ Subtract 11.4 from $38 = $26.60
- I beg your pardon for bumping this old thread, but I wanted to let you know that I'm taking a maths basics skills exam tomorrow.
I'm nervous, but re-reading all of this help here is helping me to relax.
Della

- Math basics today, Inverse Laplace transforms tomorrow!
- bump
Della

- If it hasn't already been posted: Jack Black -- The Math Song
- Maybe my mind works differently, but for 30% off a $38.50 shirt, I'd think "Hmmm 39/3 = 13, (thus) 33% off would be (roughly) $26, so I'll be charged about 27 bucks."
I was raised on Allan Sherman and Tom Lehrer, so have added a link I'm surprised I did not see furnished by anyone else in this thread (although I may have missed it).
He%20Who%20Hisses

- Thanks, r122.
Public Service bump
Della

- Look up youtube videos from Khan Academy. They are great tutors.
- Bump for a non-subscriber, innumerate friend of mine who wanted to read the thread.
Della

- For the OP. It's free.
Khan%20Academy

- thank you r126.
Della

- Della, I would be proud to help you. I've written 5 books on arithmetic.
Mr. Science

- Wow,Mr. Science at r128. That's impressive,seriously. I envy your love for numbers. Do you feel as comfortable with letters?
Anyway, I regularly re-read this entire thread thread and it helps. Thanks for wanting to add your assistance to everybody else who has done so here.
Della

- Della, you don't work at the neighborhood nuclear power facility, do you?
- No, r130. That's funny.
Della%2C%20off%20to%20the%20Khan%20Academy

- Public Service bump while I await gorging myself on Academy Awards 2014 threads.
Della

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