Mathematics for IGCSE & O level - Number (Section 1 - No. 31)
The HCF of two numbers is 5. The LCM of the same two numbers is 60. If one of the numbers is 15, what is the other number?
10
20
30
4
Explication
Using the formula: Number 1 * Number 2 = HCF * LCM. Let the unknown number be 'x'. 15 * x = 5 * 60; x = (5 * 60) / 15; x = 20.