In this activity, you will need to have an understanding of **common factors, multiples and prime numbers***.*

**Common factors:**

Common factors or factors are numbers that we multiply together to make another number.

When we find the factors of two or more numbers and then find some factors are the same **(common) **then they are called **common factors.**

**Example: 12 and 16**

**Factors of 12:** 1, 2, 3, 4, 6 and 12

**Factors of 16:** 1, 2, 4, 8 and 16

So the** common factors** of 12 and 16 are **1, 2 and 4.**

The **highest common factor** of two numbers is the largest whole number which is a factor of both.

The highest common factor of **12 **and **16 is 4.**

**Multiples: **

On multiplying a number, by counting numbers, gives us it's multiples.

A **common multiple **is a whole number that is a shared multiple of sets of numbers.

**Example: **

Multiples of 3 and 4;

**Multiples of 3**: 3, 6, 9, **12,** 15, 18, 21, **24,** 27, 30

**Multiples of 4:** 4, 8, **12**, 16, 20, **24,** 28, 32, 36, 40

The** common multiples **of 3 and 4 are: **12 and 24.**

**Prime Numbers:**

A prime number is a number only divisible **by itself and 1**.

**Example**: prime numbers between 10 and 30.

**Answer: 11, 13, 17, 19, 23, 29**.