Question

Find the least square mumber qhich is exactly divisible by each of the number 6,9,15 and 20

Answer 1

LCM of 6 9 15 20 is 3×3×5×2×2
We need to find smallest perfect square that is divisible by all of them.
if you see the LCM 3×3×5×2×2 it is not a perfect square, we know that Multiple of LCM will always be divisible by all number(i.e. 6 9 15 20). To make LCM = 3×3×5×2×2 a smallest perfect square you have to multiply it by 5.

Required no. is 3×3×5×5×2×2
= 900 which is a square of 30