Mental Math Tricks: Multiply Numbers 11-19 in Your Head

Do you struggle with multiplying numbers in your head? It can be tricky, but there are some cool mental math tricks that can help! Today, we’re going to focus on multiplying numbers between 11 and 19. This simple trick will make you a mental math whiz in no time.

The Trick

Here’s how it works:

1. Add the tens digit of the first number to the second number. For example, if you’re multiplying 13 x 17, add the tens digit of 13 (which is 1) to 17. This gives you 18.
2. Multiply the ones digit of both numbers. In our example, the ones digits are 3 and 7. Multiplying them together gives you 21.
3. Combine the results. Place the result from step 2 (21) after the result from step 1 (18). This gives you 1821.

Let’s See it in Action

Let’s try another example: 15 x 16

1. Add the tens digit of 15 (which is 1) to 16. This gives you 17.
2. Multiply the ones digits, 5 and 6. This gives you 30.
3. Combine the results: 1730.

So, 15 x 16 = 1730.

Why Does It Work?

This trick works because of how place value works. When you multiply two-digit numbers, you are essentially multiplying the tens digits, the ones digits, and then combining the results. The trick we just learned is a shortcut that combines those steps in a clever way.

Practice Makes Perfect

The best way to get good at this trick is to practice! Try multiplying different numbers between 11 and 19 using this method. You’ll be surprised how quickly you can master it.

Remember, mental math tricks are a fun and useful way to improve your math skills. So, put your thinking cap on and try this trick out! You might just impress yourself and others with your newfound math abilities.