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why...
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"1x2 is 2 2x2 is 4 3x2 is 6 4x2 is 8 5x2 is 10 6x2 is 12 7x2 is 14 8x2 is16 9x2 is 18 10x2 is 20 11x 2 is 22 12x 2 is 24 I'm a clever girl "Gold star | |||
"do we only learn our times tables up to 12 x ?? " Just a guess - but is it related to old imperial measures and pre decimal currency? 
Both of which I'm too young to know anything about! 
Any 'oldies' know the answer? | |||
"1x2 is 2 2x2 is 4 3x2 is 6 4x2 is 8 5x2 is 10 6x2 is 12 7x2 is 14 8x2 is16 9x2 is 18 10x2 is 20 11x 2 is 22 12x 2 is 24 I'm a clever girl "Copy and paste!   | |||
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"I thought maybe because we counted items in dozens but then why did we do that? We have twelve months of the year so maybe something to do with that? " Yes, it to do with eggs in dozens and bakers dozens (although that's 13) and imperial stuff. | |||
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"There used to be 12 pence in a shilling." Hence the need to be able to do mental arithmetic in 12's. | |||
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"In some schools now they are only teaching up to 10 " I think in China they go up to 20 | |||
"But why were there 12 thingys in a whatsit? Who decided we needed 12 of them? " God. That is all. | |||
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"do we only learn our times tables up to 12 x ?? " Because when you reach puberty and have a fit young female Maths teacher you tend to ignore the first 100 of 13x13 and lose focus for the rest of the lesson. | |||
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"After reading some google threads it seems that in Europe they only teach up to 10. Perhaps somebody from abroad can comment" They only need to teach up to ten really, after that you can use what you know to work out the rest. | |||
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" Quick tip for yer 9 times table. Try it works, upto 10 for obvious reasons. Place both yer hands out flat before you. Choose the number you want to multiply by 9, say 3, count from the left and fold under that finger/thumb. Now count the digits to the left of that : 2 Count the digits to the right : 7 3 x 9 is 27 Course, the quicker way is just to learn yer times table. " that's too complicated for me. I just think of the number below the number being timesed by 9 and then see what you add to it to make 9. Works up to 9x9 | |||
 let's think logically here. Who invented counting?? Traders? Farmers? The Chinese? | |||
"Google is no help with this let's think logically here. Who invented counting?? Traders? Farmers? The Chinese? "Most of the stuff has been mentioned already But google duodecimal and look at origins of 12 | |||
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"I like the hand bone counting theory " the bones in fingers? That is feasible | |||
"Is it bad that despite learning my timestables as a child, I've forgotten them all "What prompted my post was me helping my granddaughter with her tables and thinking why stop at 12,why not go up to 15 or 20? I got my 12x table wrong lol | |||
"it was to do with the money .. twelve old pennies in a shilling .. twenty shillings in a pound .. twelve also is a better base for calculations than ten . you can divide twelve by 2,3,4, giving halves, thirds and quarters .. ten only divides by .2 and 5 giving halvrs and fifths .. numbers larger than twelve can be calculated from the numbers up to twelve " I'm wondering if we used base 12 before we used money though | |||
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" Canis is correct in thinking it's 12's cos they are easy to divide and multiply. It's not from Romans as they tended to have coins in fours, so no idea really. Ps. I can be talked to/referred to with no repercussions. "do you mean me? I thought more than one person put the imperial measurements/ 12d in a shilling theory so mentioned no names to save leaving someone out.  | |||
"my brother is a math genius he will know the answer" please ask him and let me know if he knows | |||
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"There was a time - several decades ago now - when the reason for learning the 12 times table was obvious. As a country using imperial measurements, we were all measuring in feet and inches and paying in shillings and pence, so multiplying by 12 was a common, everyday experience. But for today's children this is all ancient history. Yes, we do still count eggs in dozens, and a lot of people - including most Americans - do still work in inches, but that's hardly justification for spending hours swotting those extra tables. And yet, there's still a case for learning your "twelves", but the reason is to do with discovering patterns and building a confidence in handling numbers. Once children begin to get comfortable multiplying numbers larger than 10, they start to get a feel for big multiplications. Knowing your 11 and 12 times tables can introduce intriguing patterns that might be missed if you stop at 10. Much of the 11 times table is trivial to learn: 2 times 11 is 22, 8 times 11 is 88. And even when you get beyond 12, there are nice patterns to discover. Want to multiply 11 by 23? Just take the two digits 2 and 3, add them together (makes 5) and put that number in the middle - 253. What about 36 x 11? Again, split the 3 and the 6 and put their sum (9) in the middle - 396. Lovely - though take care, if the two digits add to more than 9, this nifty trick doesn't work so neatly. 58 x 11... well 5+8 = 13, but the answer isn't 5138, that "1" actually represents a 100, and needs to be added to the 5 to give the answer 638. There's a pattern that begins with 11 x 11, too. Multiply those two numbers together and you get 121. How about 111 x 111? The answer is 12321. Care to guess what 1111 x 1111 is? Yes, 1234321. Meanwhile multiplying by 12 becomes much simpler when you realise it's the same as multiplying a number by 10 and then adding on double the start number. So 12 x 12 is 10 x 12 (=120) and then add 2 x 12 (=24) to give 120+24 = 144. This rule doesn't stop at your tables - 12 x 61 is the same as 10 x 61 (=610) plus 2 x 61 (=122) and if you can add 610 + 122 in your head you have the right answer, 732. Do you need to memorise the answer to 12 x 12? Well, not really. As long as you know the strategy for working it out, you can get there almost as quickly by recalculating it in your head. But, of course, if you do a calculation often enough, it will become embedded in your memory, which will speed things up on those occasions when you need the answer. Why stop at 12? You can continue to 13, 14… all the way up to 20 times table, as I believe happens in some countries. But hang on, if you understand your basic times tables up to 10, then you have the essential tools you need for working out, say, 19 x 14. And if you spend too much time rote learning the answers to these questions then you're going to miss out on time spent understanding how numbers work. And it's understanding patterns and solving problems that maths is really all about. " very interesting | |||
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" Quick tip for yer 9 times table. Try it works, upto 10 for obvious reasons. Place both yer hands out flat before you. Choose the number you want to multiply by 9, say 3, count from the left and fold under that finger/thumb. Now count the digits to the left of that : 2 Count the digits to the right : 7 3 x 9 is 27 Course, the quicker way is just to learn yer times table. that's too complicated for me. I just think of the number below the number being timesed by 9 and then see what you add to it to make 9. Works up to 9x9 " Works for infinity | |||
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"I think learning up to 12 x 12 is gross..... Boom Boom !" Granny, wise beyond her years | |||
"There was a time - several decades ago now - when the reason for learning the 12 times table was obvious. As a country using imperial measurements, we were all measuring in feet and inches and paying in shillings and pence, so multiplying by 12 was a common, everyday experience. But for today's children this is all ancient history. Yes, we do still count eggs in dozens, and a lot of people - including most Americans - do still work in inches, but that's hardly justification for spending hours swotting those extra tables. And yet, there's still a case for learning your "twelves", but the reason is to do with discovering patterns and building a confidence in handling numbers. Once children begin to get comfortable multiplying numbers larger than 10, they start to get a feel for big multiplications. Knowing your 11 and 12 times tables can introduce intriguing patterns that might be missed if you stop at 10. Much of the 11 times table is trivial to learn: 2 times 11 is 22, 8 times 11 is 88. And even when you get beyond 12, there are nice patterns to discover. Want to multiply 11 by 23? Just take the two digits 2 and 3, add them together (makes 5) and put that number in the middle - 253. What about 36 x 11? Again, split the 3 and the 6 and put their sum (9) in the middle - 396. Lovely - though take care, if the two digits add to more than 9, this nifty trick doesn't work so neatly. 58 x 11... well 5+8 = 13, but the answer isn't 5138, that "1" actually represents a 100, and needs to be added to the 5 to give the answer 638. There's a pattern that begins with 11 x 11, too. Multiply those two numbers together and you get 121. How about 111 x 111? The answer is 12321. Care to guess what 1111 x 1111 is? Yes, 1234321. Meanwhile multiplying by 12 becomes much simpler when you realise it's the same as multiplying a number by 10 and then adding on double the start number. So 12 x 12 is 10 x 12 (=120) and then add 2 x 12 (=24) to give 120+24 = 144. This rule doesn't stop at your tables - 12 x 61 is the same as 10 x 61 (=610) plus 2 x 61 (=122) and if you can add 610 + 122 in your head you have the right answer, 732. Do you need to memorise the answer to 12 x 12? Well, not really. As long as you know the strategy for working it out, you can get there almost as quickly by recalculating it in your head. But, of course, if you do a calculation often enough, it will become embedded in your memory, which will speed things up on those occasions when you need the answer. Why stop at 12? You can continue to 13, 14… all the way up to 20 times table, as I believe happens in some countries. But hang on, if you understand your basic times tables up to 10, then you have the essential tools you need for working out, say, 19 x 14. And if you spend too much time rote learning the answers to these questions then you're going to miss out on time spent understanding how numbers work. And it's understanding patterns and solving problems that maths is really all about. " Take a bow, young lady | |||
"I think learning up to 12 x 12 is gross..... Boom Boom !" lol made me laugh out loud that did | |||
" Quick tip for yer 9 times table. Try it works, upto 10 for obvious reasons. Place both yer hands out flat before you. Choose the number you want to multiply by 9, say 3, count from the left and fold under that finger/thumb. Now count the digits to the left of that : 2 Count the digits to the right : 7 3 x 9 is 27 Course, the quicker way is just to learn yer times table. that's too complicated for me. I just think of the number below the number being timesed by 9 and then see what you add to it to make 9. Works up to 9x9 Works for infinity" 9x1 = 9 9x2 = 18 1+8=9 9x3 = 27 2+7=9 ad nauseam, even 9x17=153 1+5+3=9.......spooky. | |||
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" Quick tip for yer 9 times table. Try it works, upto 10 for obvious reasons. Place both yer hands out flat before you. Choose the number you want to multiply by 9, say 3, count from the left and fold under that finger/thumb. Now count the digits to the left of that : 2 Count the digits to the right : 7 3 x 9 is 27 Course, the quicker way is just to learn yer times table. that's too complicated for me. I just think of the number below the number being timesed by 9 and then see what you add to it to make 9. Works up to 9x9 Works for infinity 9x1 = 9 9x2 = 18 1+8=9 9x3 = 27 2+7=9 ad nauseam, even 9x17=153 1+5+3=9.......spooky." but you have to work out 9x17 first, can't do it using my easy method of going one lower and adding up to make 9  | |||
" If you stop at 10x10, you miss one of the interesting patterns. 11x11=121 111x111=12321 Learnt before calculators were common. " 58008 | |||
" If you stop at 10x10, you miss one of the interesting patterns. 11x11=121 111x111=12321 Learnt before calculators were common. 58008 " | |||
" Quick tip for yer 9 times table. Try it works, upto 10 for obvious reasons. Place both yer hands out flat before you. Choose the number you want to multiply by 9, say 3, count from the left and fold under that finger/thumb. Now count the digits to the left of that : 2 Count the digits to the right : 7 3 x 9 is 27 Course, the quicker way is just to learn yer times table. that's too complicated for me. I just think of the number below the number being timesed by 9 and then see what you add to it to make 9. Works up to 9x9 Works for infinity 9x1 = 9 9x2 = 18 1+8=9 9x3 = 27 2+7=9 ad nauseam, even 9x17=153 1+5+3=9.......spooky. but you have to work out 9x17 first, can't do it using my easy method of going one lower and adding up to make 9 "It's not a method, it's just one of the sequential patterns that emerge when you learn your tables by rote. | |||
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"But why were there 12 thingys in a whatsit? Who decided we needed 12 of them? " That's easy... 12 thingys make a whatsit and 4 whatsits make a doberry so when you revert this to decimals it simplifies itself to the lowest common denominator ( give or take 1 or 2 decimal places ) me thinks lol  | |||
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"But why were there 12 thingys in a whatsit? Who decided we needed 12 of them? That's easy... 12 thingys make a whatsit and 4 whatsits make a doberry so when you revert this to decimals it simplifies itself to the lowest common denominator ( give or take 1 or 2 decimal places ) me thinks lol "you had to go and complicate it with your decimals didn't you. Now I'm lost  | |||
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"There was a time - several decades ago now - when the reason for learning the 12 times table was obvious. As a country using imperial measurements, we were all measuring in feet and inches and paying in shillings and pence, so multiplying by 12 was a common, everyday experience. But for today's children this is all ancient history. Yes, we do still count eggs in dozens, and a lot of people - including most Americans - do still work in inches, but that's hardly justification for spending hours swotting those extra tables. And yet, there's still a case for learning your "twelves", but the reason is to do with discovering patterns and building a confidence in handling numbers. Once children begin to get comfortable multiplying numbers larger than 10, they start to get a feel for big multiplications. Knowing your 11 and 12 times tables can introduce intriguing patterns that might be missed if you stop at 10. Much of the 11 times table is trivial to learn: 2 times 11 is 22, 8 times 11 is 88. And even when you get beyond 12, there are nice patterns to discover. Want to multiply 11 by 23? Just take the two digits 2 and 3, add them together (makes 5) and put that number in the middle - 253. What about 36 x 11? Again, split the 3 and the 6 and put their sum (9) in the middle - 396. Lovely - though take care, if the two digits add to more than 9, this nifty trick doesn't work so neatly. 58 x 11... well 5+8 = 13, but the answer isn't 5138, that "1" actually represents a 100, and needs to be added to the 5 to give the answer 638. There's a pattern that begins with 11 x 11, too. Multiply those two numbers together and you get 121. How about 111 x 111? The answer is 12321. Care to guess what 1111 x 1111 is? Yes, 1234321. Meanwhile multiplying by 12 becomes much simpler when you realise it's the same as multiplying a number by 10 and then adding on double the start number. So 12 x 12 is 10 x 12 (=120) and then add 2 x 12 (=24) to give 120+24 = 144. This rule doesn't stop at your tables - 12 x 61 is the same as 10 x 61 (=610) plus 2 x 61 (=122) and if you can add 610 + 122 in your head you have the right answer, 732. Do you need to memorise the answer to 12 x 12? Well, not really. As long as you know the strategy for working it out, you can get there almost as quickly by recalculating it in your head. But, of course, if you do a calculation often enough, it will become embedded in your memory, which will speed things up on those occasions when you need the answer. Why stop at 12? You can continue to 13, 14… all the way up to 20 times table, as I believe happens in some countries. But hang on, if you understand your basic times tables up to 10, then you have the essential tools you need for working out, say, 19 x 14. And if you spend too much time rote learning the answers to these questions then you're going to miss out on time spent understanding how numbers work. And it's understanding patterns and solving problems that maths is really all about. "
Far out!!! | |||
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"I'm shocking with numbers "Lolz - I wasn't going to bother reading this thread but thanks to that particular post - I'm really glad I did now!! | |||
