Question

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

Hint:

List the prime factors of each number and take the product of the lowest powers of common factors.

Answer 1

Prime factorisations: \[ 180 = 2^2 \times 3^2 \times 5
140 = 2^2 \times 5 \times 7
210 = 2 \times 3 \times 5 \times 7 \] Common prime factors in all three numbers = \(2^1 \times 5 = 10\)