Question

What is the least common multiple of 6 and 15? A) 3 B) 9 C) 21 D) 30

Answer 1

`6=2\cdot3\\15=3\cdot5\\\\\text{lcm}(6,15)=2\cdot3\cdot5=30`

Answer 2

D

Explanation:

multiples of 6 : 6, 12, 18, 24, 30, 36, ....

multiples of 15 : 15, 30, 45, ......

From the lists the least common multiple is 30