Page 71 - Maths Class 04

Example : Find the common factors of 12 and 16.
Solution : Factors of 12 Factors of 16

1 × 12 = 12 1 × 16 = 16

2 × 6 = 12 2 × 8 = 16

3 × 4 = 12 4 × 4 = 16

Factors of 12 are 1, 2, 3, 4, 6 and 12 Factors of 16 are 1, 2, 4, 8 and 16

Factors of 12 Factors of 16

Factors Factors
of 12 of 16
1, 2, 3, 4, 6, 12 1, 2, 4, 8, 16
3 1 8
6 2 16
12 4

Common factors of 12 and 16 are 1, 2 and 4.

Example : Find the common factors of 14 and 36.

Solution : Factors of 14 are 1, 2, 7 and 14.

Factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18 and 36.

Factors of 14 Factors of 36
3,
12,
1, 2, 7, 14 7, 1, 4, 18, 1, 2, 3, 4, 6, 9, 12, 18, 36
14 2 6, 36
9,

Common factors of 14 and 36 are 1 and 2.

Highest Common Factor (HCF) or Greatest Common Factor (GCF)

This method is used to find the largest factor that divides two numbers

exactly without leaving a remainder. We call this the Highest Common

Factor (HCF).

Let us find the HCF of 30 and 45.

First, find the prime factors of each number, using prime factorisation.

30 = 2 × 3 × 5

45 = 3 × 3 × 5

Mathematics-4 71