Now we’re going to figure out the missing numbers in these equations…like a detective!

Instead of filling in an empty box, we’ll be filling an empty spot in an equation—in other words, a math sentence like this:

4 + ? = 10

We can read this math sentence by using the word “what” where we see the question mark: “Four plus what equals ten?” Try saying that out loud!

And what’s the answer? 6! And the math sentence becomes 4 + 6 = 10. Nice! And instead of a question mark, we could use a flower or a car, or even a letter like x, y, or z! It doesn’t matter what is in that spot—our job is to figure out what number goes in that spot to make the math sentence true.

Here’s an example!

9 − = 4

We know the must be standing in for 5, because that’s the number that makes the math sentence true: 9 − 5 = 4. See?

Here are some more:

4 + 2 =

The must be 6, since 4 + 2 = 6.

– 2 = 7

The must be 9, since 9 − 2 = 7.

10 – ? = 3

The ? must be 7, since 10 − 7 = 3.