Tens Complement

What Makes 10?

The "Tens Complement" is the number that you add to make 10:

Example: The Tens Complement of 3 is 7, because 3+7=10

Here are all the Tens Complements:

Number Tens Complement Why? Because:
0 10 0 + 10 = 10
1 9 1 + 9 = 10
2 8 2 + 8 = 10
3 7 3 + 7 = 10
4 6 4 + 6 = 10
5 5 5 + 5 = 10
6 4 6 + 4 = 10
7 3 7 + 3 = 10
8 2 8 + 2 = 10
9 1 9 + 1 = 10
10 0 10 + 0 = 10

But you only have to remember half the table!

If you know that 1 + 9 = 10, you should also know that 9 + 1 = 10

1 and 9 are partners!

So are 2 and 8, 3 and 7, 4 and 6 and 5 and 5

Why is this Important?

If you know your Tens Complements it makes some mental arithmetic a whole lot easier.

For example it is used in Quick Subtraction.

Practice!

You can practice by using What Makes 10?