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Learning the Times Tables

In the US, children are typically expected to memorize the times table from 1×1 up to 12x12 before leaving elementary school. I learned them in 4th grade.

Reality: There's a small number of answers you need to memorize. Most can be easily and quickly found via tricks.

For starters, since it doesn't matter what order you multiply in, about half the chart is a duplicate of the other half of the chart. If you know the answer for 6x8 you also know the answer for 8x6: 48.

1.
1 times anything is the number you multiplied by one. There's nothing you need to memorize. 

2.
Any whole number multiplied by 2 will result in an even number.  

5.
All whole numbers multiplied by 5 will end in a 5 or a 0. If it's an odd number, it ends in 5. If it's an even number, it ends in zero.

It's typically easier to multiply by 10 then divide by 2. This can work for quite large figures, especially if it's a round number like 1000 or 1500.

1000x5 doesn't really require that. 1×5=5, 1000x5 =5000.

1500x10 =15,000 ÷2 =7500.

For small numbers, you skip count until you get to the other number times 5: 5-10-15-20 etc.

9.
This movie scene (contains a rude gesture) shows a math teacher multiplying by nine on his fingers. 

All multiples of 9 result in an answer that adds up to 9. For numbers under 10, subtract 1 from the multiplier and make the "remainder" of 9 your second number.

9x1 =9
9x2 =18
9x3 =27
9x4 =36
9×5 =45
9×6 =54
9×7 =63
9x8 =72
9x9 =81

10.
Just add zero or move the decimal place if appropriate.  Done.

2x10 =20
132×10 =1320
2.13x10 =21.3

11.
If it's a single digit, just place two copies of the number next to each other.

11x1 =11
11x2 =22
11x3 =33

If it's larger than that, stack them and add. You are effectively multiplying by ten plus one.

11x11=
110
+11
------
121

11x12
120
+12
------
132

You are still just placing two copies of the number next to each other,  but the the numbers "overlap."
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