6 colours and 4 sizes, how many shirts

Step by step

The question

Question: There are 6 colours and 4 sizes.

How many shirts can be made with one of each?

1 Count the choices

2 Multiply

Each of the 6 colours goes with 4 sizes.

So we multiply: 6 × 4.

This is the counting principle: multiply the number of choices.

6 groups of 4: that is 6 times 4.

Careful!

We do not add the choices.

Every choice goes with every other one, so we multiply.

6 times 4 is 24.

So there are 24 shirts.

3 Check

Let's check: 24 divided by 6 is 4.

That gives back the 4 choices.

So the answer is right!

Let's look back.

First: count the choices.

Then: multiply.

Last: check.