# How can multiples of ten make multiplication easier?

## What are multiples of ten?

Numbers like **2**, **3** or **5** are quite small and straightforward.

Numbers like **20**, **30** or **50** are bigger and the **0** at the end might seem confusing.

We call these numbers multiples of ten because we can think of them as numbers of groups of ten:

**20** is **2** groups of **10**

**30** is **3** groups of **10**

**50** is **5** groups of **10**

How can you multiply by multiples of **10**?

If you have to multiply by **20**, remember that this is **2** groups of **10**, or **2 x 10**.

So you might find it easier to multiply by **2** first, then multiply your answer by **10**.

## Example

**3 x 40 = ?**

Remember that **40** is the same as **4 x 10**

So first do **3 x 4 = 12**

Then multiply this by **10**

**12 x 10 = 120**

You've just worked out that **3 x 40 = 120**

What about dividing? You can do something similar when dividing. First divide by the number of groups of 10, then divide by 10.

## Example

**140 ÷ 20 = ?**

Remember that **20** is the same as **2 x 10**

So first do **140 ÷ 2 = 70**

Then divide this by **10**

**70 ÷ 10 = 7**

You've just worked out that **140 ÷ 20 = 7**

Well done.