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Shortcuts for Mastering Your Multiplication Tables

In a recent post, I wrote about the importance of memorizing your multiplication tables, and mentioned some shortcuts that can be helpful. I'm honestly still an advocate for truly memorizing as much of your multiplication tables as possible, as I believe it'll be the fastest way to arrive at the right answer.

But in this post, I wanted to be a bit more comprehensive about shortcuts for multiplying up to 12 that can be helpful if needed (or can sometimes be helpful in double-checking your answer):

  • Multiplying by 0 – Anything times 0 is always 0.
  • Multiplying by 1 – Any number times 1 stays the same.
  • Multiplying by 2 – Just double the number (e.g., 7 × 2 = 14).
  • Multiplying by 3 – The sum of the digits in your answer is always divisible by 3 (e.g., 3 x 8 = 24, and 2 + 4 = 6, which is divisible by 3). While not really a trick to arrive at your answer, it can be a good way to double-check if your answer is correct.
  • Multiplying by 5 – The answer always ends in 0 or 5, and you can halve the 10 times table (e.g., 5 × 8 → 10 × 8 = 80, then 80 ÷ 2 = 40).
  • Multiplying by 9 – Use the hand trick: Hold out both hands, put down the finger for the number you're multiplying (e.g., for 9 × 7, put down your seventh finger—6 fingers are left to the left, 3 to the right, so the answer is 63). Of course, this only works to 9 x 10.
  • Multiplying by 10 – Just add a zero to the end of the number (e.g., 10 × 7 = 70).
  • Multiplying by 11 – Up to 9, just double the digit (e.g., 11 × 6 = 66). For 11 × 10 and higher, add the two digits and place the sum in the middle (e.g., 11 × 12 → 1 (1+2) 2 = 132).
  • Multiplying by 12 – Think of 12 as 10 + 2: Multiply by 10, then add twice the number (e.g., 12 × 4 → 10 × 4 = 40, then add 4 × 2 = 8 → 40 + 8 = 48).

Do you know of any other good tricks that I've missed?  If so, please leave them in the comments below!

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