Finding Unknown Numbers

Front

4 + ? = 12

Back

8

Front

3 + ? = 12

Back

9

Front

15 + __ = 21

Back

6

Front

4 + __ = 7

Back

3

Front

6 + ? = 15

Back

9

Front

What is an addend?

Back

An addend is a number that is added to another number.

Front

What is the sum?

Back

The sum is the result of adding two or more numbers together.

Front

If 5 + ? = 10, what is the missing number?

Back

5

Front

What does it mean to find an unknown number?

Back

It means to determine a number that makes an equation true.

Front

If 2 + ? = 5, what is the missing number?

Back

3