#### Multiplying by a Multiple of 10

- A multiple of 10 is a number in the 10 times table.
- To multiply a whole number by 10, simply write a zero digit on the end of it.
- To multiply a number by a multiple of 10, multiply the number digits in front of the 0 digit and then write a 0 on the end.
- 20 is a multiple of 10. 20 is 2 × 10.
- To work out 5 × 20, we can work out 5 × 2 × 10.
- 5 × 2 = 10 and now we just need to multiply by 10.
- To multiply 10 by 10, we simply write a 0 digit on the end.
- 10 × 10 = 100 and so, 5 × 20 = 100.

#### Multiplying by a Multiple of 100

- A multiple of 100 is a number in the 100 times table.
- To multiply a whole number by 100, simply write two 0 digits on the end of it.
- To multiply a number by a multiple of 100, multiply the number by the digits in front of the two 0 digits and then write two 0 digits on the end.
- 400 is a multiple of 100. 400 = 4 × 100.
- To work out 7 × 400, we can work out 7 × 4 × 100.
- 7 × 4 = 28 and now we just need to multiply by 100.
- To multiply 28 by 100 we simply write two 0 digits on the end.
- 28 × 100 = 2800 and so, 7 × 400 = 2800.

**Multiply the number by the first digits of the multiple of 10 or 100.**

**Write the same number of zeros on the end of the answer as there are in 10 or 100.**

- 110 is a multiple of 10 because it ends in one 0 digit.
- 110 = 11 × 10 so to multiply 6 by 110, we will multiply 6 × 11 × 10.
- 6 × 11 = 66 and we will multiply by 10 by writing a 0 on the end.
- 66 × 10 = 660 and so, 6 × 110 = 660.

#### Multiplying by Multiples of 10 and 100: Interactive Questions

Multiplying by Multiples of 10 and 100: Interactive Questions

#### Multiplying by Multiples of 10 and 100 Worksheets and Answers

# Multiplying by Multiples of 10 and 100

## What is a Multiple of 10?

**A multiple of 10 is a number in the 10 times table. Multiples of 10 will always have a last digit of 0. The first few multiples of 10 are 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100.**

We can recognise multiples of 10 because they are numbers that end in at least one 0 digit.

## What is a Multiple of 100?

**A multiple of 100 is a number in the 100 times table. Multiples of 100 will always have two 0 digits as their last two digits. The first few multiples of 100 are 100, 200, 300, 400, 500, 600, 700, 800, 900 and 1000.**

We can recognise multiples of 100 because they are numbers that end in at least two 0 digits.

## How to Multiply by Multiples of 10

**To multiply a whole number by a multiple of 10, follow these steps:
**

**
**

**Multiply the whole number by the digits in front of the last 0 in the multiple of 10.**- Multiply this result by 10 by writing a 0 digit on the end.

For example, we will multiply 5 × 20.

20 is a multiple of 10 because it ends in a 0 digit.

We can write multiples of 10 as the digits in front of the zero digit multiplied by 10. For example, 20 = 2 × 10.

Multiplying by 20 is the same as multiplying by 2 and then by 10.

To multiply 5 × 20, we multiply 5 × 2 × 10.

5 × 2 = 10.

10 × 10 = 100. To multiply a whole number by 10, simply write a 0 digit on the end. 10 becomes 100.

5 × 20 = 5 × 2 × 10 = 10 × 10 = 100. Therefore 5 × 20 = 100.

To multiply by a multiple of 10, simply multiply the digits ignoring the last 0 digit and then write the 0 digit back in at the end.

Because 5 × 2 = 10, 5 × 20 = 100.

Here is another example of multiplying by a multiple of 10. We have 6 x 110.

110 is a multiple of 10 because it ends in a 0.

6 x 11 = 66 and so, 6 x 110 = 660.

## How to Multiply by Multiples of 100

**To multiply a whole number by a multiple of 100, follow these steps:
**

**
**

**Multiply the whole number by the digits in front of the last two 0 digits in the multiple of 100.**- Multiply this result by 100 by writing two 0 digits on the end.

For example, here is 7 × 400. 400 is a multiple of 100 because it ends in 2 zero digits.

We multiply 7 by 4 and then write two 0 digits on the end to multiply by 100.

Multiplying by 400 is the same as multiplying by 4 and then 100.

7 x 400 is the same as 7 x 4 x 100.

4 x7 = 28. We now need to multiply by 100.

To multiply a whole number by 100, simply write two 0 digits on the end.

28 x 100 = 2800. Therefore 7 x 400 = 2800.

Because 7 x 4 = 28, 7 x 400 = 2800.

Here is another example of multiplying by a multiple of 100. We have 12 x 500.

500 is a multiple of 100 because it ends in 2 zero digits.

12 x 5 = 60 and so, 12 x 500 = 6000.

We simply write 2 more zeros on the end of 60 to make 6000.

Now try our lesson on *Multiplying by 4 and 8 Using Doubling* where we learn how to use doubling to multiply by 4 and 8.