- Books Name
- CBSE Class 6 Mathematics Book

- Publication
- Param Publication

- Course
- CBSE Class 6

- Subject
- Mathmatics

**Common Factors **

The factors of 4 are 1, 2 and 4.

The factors of 18 are 1, 2, 3, 6, 9 and 18. The numbers 1 and 2 are the factors of both 4 and 18.

They are the common factors of 4 and 18.

Two numbers having only 1 as a common factor are called **co-prime numbers**. Thus, 4 and 15 are

**co-prime numbers.**

**Common Multiples**

The multiples of 4 are 4, 8, 12, 16, 20, 24, ...

The multiples of 6 are 6, 12, 18, 24, 30, 36, ...

We observe that 12, 24, 36, ... are multiples of both 4 and 6.

They are called the common multiples of 4 and 6.

**Ex. ** Find the common multiples of 3, 5 and 6.

**Sol. ** Multiples of 3 are 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, ...

Multiples of 5 are 5, 10, 15, 20, 25, 30, 35, ...

Multiples of 6 are 6, 12, 18, 24, 30, ...

Common multiples of 3, 5 and 6 are 30, 60, ...