# Factors

## Home learning focus

In this lesson, you will learn about factors, square numbers and prime numbers.

This lesson includes:

- a video
- a learning summary
- three activities

# Learn

## Factors

A **factor** is a number that divides into another number exactly and without leaving a remainder.

The number 12 has **six** factors:

1, 2, 3, 4, 6 and 12

If 12 is divided by any of the six factors then the answer will be a **whole number**.

For example: 12 ÷ 3 = 4

Watch this short video from BBC Bitesize to find out more.

## Square numbers

Square numbers are formed by **multiplying a number by itself**. All square numbers have an **odd number of factors**. For example, the number 25 has **three** factors:

1, 5 and 25

And the number 16 has **five** factors:

1, 2, 4, 8 and 16

## Prime numbers

A prime number is a number which is only divisible by **1 and itself**. Prime numbers cannot be divided by another number to leave a whole number.

Prime numbers include:

2, 3, 5, 7, 11, 13, 17, 19, 23 and 29.

The number 59 is prime because it is only divisible by **1** and **59**.

The number 51 is **not** prime because it is divisible by **3** and **17** as well as **1** and **51**.

The number 1 only has one factor (itself). Therefore, **1 is not a prime number**.

# Practise

## Activity 1

**Quiz**

Find out how much you know about factors in this short quiz!

## Activity 2

**Find the factors**

Have a go at this interactive activity from My Maths, Oxford University Press.

Find the factors of different numbers.

Watch out - if you select two incorrect answers it's game over!

## Activity 3

**Worksheet: Factors**

Have a go at this worksheet from Whizz Education.

You can print it out or write your answers on a piece of paper.

# There's more to learn

Have a look at these other resources around the BBC and the web.