Question

Using prime factorisation, find the HCF of 180, 140 and 210.

Answer 1

HCF (180, 140, 210)

Prime factorisation of 180, 140, 210

2	180
2	90
3	45
3	15
5	5
	1

2² × 3² × 5

2	140
2	70
5	35
7	7
	1

2² × 5 × 7

2	210
3	105
5	35
7	7
	1

2 × 3 × 5 × 7

The common factors are 2 and 5.

HCF = 2 × 5

HCF = 10