Calculate 50 × 9 × 2 × 3 in your head

Step by step

The question

Question: work out 50 × 9 × 2 × 3 in your head.

1 Find the easy pair

Look for two numbers that make a round number.

50 times 2 is 100.

That is easy.

2 Change the order

We move 2 next to 50.

In multiplying, the order does not matter.

This is the commutative property.

3 Group the easy pair

We put brackets round the easy pair, so we do it first.

With only multiplying, we can group the numbers any way we like.

This is the associative property.

Careful!

This works for multiplying only.

With minus or divide, the order matters.

4 Work it out

50 times 2 is 100.

900 times 9 is 900.

900 times 3 is 2700.

5 Check

Let's check the long way, from left to right: 50 times 9 is 450.

450 times 2 is 900.

900 times 3 is 2700.

The same.

So the answer is right!

Let's look back.

First: find the easy pair.

Then: change the order.

Then: group the easy pair.

Then: work it out.

Last: check.