# Grade 5, Maths Olympiad (CBSE) - Factors

## Factors

Factors of a number are the numbers which divide the number completely without leaving a remainder. A number can have multiple factors.

E.g.

Factors of 12=3 X 4, 1 X 12, 2 X 6, 2 X 2 X 3

Prime factors: If factors of a number are prime numbers then they are called prime factors.

E.g.

Prime factors of 12=1 X 2 X 2 X 3

Common factors: Factor common between two numbers are called common factors.

E.g.

9=1 X 3 X 3

6=1 X 2 X 3

1 and 3 are common between the two numbers thus they are common factors between the two numbers.

H.C.F. of two numbers is the greatest common factor which divides the two numbers completely. It is also known as G.C.F or greatest common factor.

E.g.

12=1 X 2 X 2 X 3 , 2 X 6

18=1 X 2 X 3 X 3 , 3 X 6

Common factors between 12 and 18 are 1, 2, 3 and 6. 6 is the greatest among all factors so 6 is the H.C.F. of 12 and 18

Co-prime: If two numbers have only 1 as the common factor they are known as co-prime numbers. E.g. 3 and 5. 