Multiply when 10's Digits are Equal

Many people use the FOIL method to multiply two digit numbers but if the ten's digits are the same and the one's digits add up to 10 there is a much easier way to solve the problem.

Look at the math problem 43 x 47 = ? Let's see how the trick works.

• Take the ten's digit and multiply it by the next highest number. In this example 4 X 5 = 20. Write 20.
• Next multiply 3 x 7 = 21. Write 21.
• ANSWER is 2021.

Let's look at another example. 84 x 86 = ?

• Multiply 8 by the next greatest number. 8 x 9 = 72. Write 72.
• Multiply 4 x 6 = 24. Write 24.

ANSWER is 7224.

Watch the math video below for a detailed explanation!

Practice Math Problems

1. What does 43 x 47 equal?
2. What does 36 x 34 equal?
3. What does 53 x 57 equal?
4. What does 17 x 13 equal?
5. What does 22 x 28 equal?
6. What does 82 x 88 equal?
7. What does 66 x 64 equal?
8. What does 29 x 21 equal?
9. What does 91 x 99 equal?
10. What does 102 x 108 equal?