A factor of a given number is every number that divides the given number.

Example

16 = 2 x 8, so numbers 2 and 8 are factors of 16.

Also 16 = 16 x 1, so 16 and 1 are factors of 16.

Also 16 = 4 x 4 ,so 4 is a factor of 16

The factors of 10 are 1, 2,4, 8, and 16.

NOTE: Number 1 and the number itself are always factors of any number.

COMMON FACTORS:

When two (or more) numbers have the same factor, that factor is called a common factor.

Example

Factors of 12 are 1, 2, 3, 4, 6, 12.

Factors of 18 are 1, 2, 3, 6, 18.

The common factors of 12 and 18 are 1, 2, 3 and 6.

HIGHEST COMMON FACTOR:

The Highest Common Factor (H.C.F) of two (or more) numbers is the largest number that divides both the numbers. It is also known as G.C.D. (Greatest common divisor)

In other words the H.C.F is the Highest common factors.