## Blog OLD ID: 36

The common errors children make are mixing up the answers 63 and 64, and 56 and 54. If your child has a tendency to confuse the answers to 7x9 and 8x8 or 7x8 and 6x9, you can sometimes help them sort it out by working from the answer back to the factors.

A good starting point is talking about patterns of the answers when you have odd x odd, even x even or odd x even. Start with the 2x table and you’ll notice all the answers are even. Look at the other times tables – it always works. If you’ve got an even number as a factor, the product (answer) will be even.

So how can you get an odd product (answer)? Only if BOTH factors are odd. Hence an answer of 63 could only come from two odd numbers being multiplied – therefore it can’t be the answer to 8x8.

Continuing our perusal of answers, take a close look at the multiples of 9. If you add their digits, all the answers to the 9x table add to nine. eg 18 (1+8=9), 27 (2+7=9), 36 (3+6=9) etc.

It always works, and it works both ways. If you have a number with a digit sum of 9 you know you have a multiple of nine. Eg 67392: 6+7+3+9+2=27, 2+7=9 so 67392 has a digit sum of 9, therefore 9x something must equal 67392 and sure enough, 9x 7488=67392

You can use this interesting fact about the 9x table to instantly recognize 63 as a multiple of 9 (because 6+3=9) and 54 as a multiple of 9 (because 5+4=9).

Taking time to really examine the answers like this gives children more information about the times tables they are trying to rote learn. Simple tricks like this can help clear up 63/64 and 54/56 confusion because more information makes things easier to remember.

Posted on 06/05/2015