Use these easy steps to quickly multiply any number between 10 and 20 by another number between 10 and 20. Anything from 11-19 – we are talking about some big numbers that you probably aren’t going to memorize – so it helps to have a fast way to do them.
The steps may seem a bit ”tricky” at first, but try it a few times and you’ll have it down – and you will have a huge multiplication timesaver in your toolbox, and maybe a cool party trick too.
Let’s use 16 x 14 for an example. We’ll only need the larger number and the ones digit from the smaller number (16 and the 4 from 14).
Here are the steps:
1. Add the larger number and the ones digit from the smaller – 16 + 4 = 20
2. Multiply this by 10 (add a zero behind it) to get 200, (part 1)
3. Now, multiply the 4 by the ones digit in the larger number, 6, so 4 x 6 to get 24, (part 2)
4. Add part 1 to part 2, or 200 and 24 from above, 200 + 24 = 224, which is the answer to 16 x 14.
Try this for yourself –
19 x 19 = is it 361 or 316?
12 x 18 = is it 206 or 216?
17 x 16 = is it 262 or 272?
Amaze your friends and family, and then teach them the trick!