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Multiplication Tips and Tricks

Some Tips and Tricks

Here are some tricks that may help you remember your times tables. Everyone thinks differently, so just ignore any tricks that don't make sense to you.

Every entry has a twin, which may be easier to remember. For example if you forget 8×5, you might remember 5×8. This way, you only have to remember half the table.


to multiply by
Trick
2
add the number to itself (example 2×9 = 9+9)
5
The last digit always goes 5,0,5,0,..,
is always half of 10× (Example: 5x6 = half of 10x6 = half of 60 = 30)
is half the number times 10 (Example: 5x6 = 10x3 = 30)
6
if you multiply 6 by an even number, they both end in the same digit. Example: 6×2=12, 6×4=24, 6×6=36, etc
9
is 10× the number minus the number. Example: 9×6 = 10×6 - 6 = 60-6 = 54
The last digit always goes 9,8,7,6, ..
if you add the answer's digits together, you get 9. Example: 9×5=45 and 4+5=9. (But not with 9×11=99)
10
put a zero after it
11
up to 9x11: just repeat the digit (Example: 4x11 = 44)
  for 10x11 to 18x11: write the sum of the digits between the digits (Example: 15x11 = 1(1+5)5 = 165)

Note: this works for any two-digit number, but if the sum of the digits is more than 9, you will have to "carry the one" (Example: 75x11 = 7(7+5)5 = 7(12)5 = 825).
12
is 10× plus 2×

Remembering Squares Can Help

This may not work for you, but it worked for me. I like remembering the squares (where you multiply a number by itself):

1×1=1 2×2=4 3×3=9 4×4=16 5×5=25 6×6=36
           
7×7=49 8×8=64 9×9=81 10×10=100 11×11=121 12×12=144

And this gives me one more trick. if the numbers you are multiplying are separated by 2 (example 7 and 5), then multiply the number in the middle by itself and subtract one. See this:

5×5 = 25 is just one bigger than 6×4 = 24
6×6 = 36 is just one bigger than 7×5 = 35
7×7 = 49 is just one bigger than 8×6 = 48
8×8 = 64 is just one bigger than 9×7 = 63
etc ...

If you have any more neat tricks, just tell us at the forum.