The least perfect square, which is divisible by each of 21, 36 and 66 is:


A. 213444
B. 214344
C. 214434
D. 231444

A?

2 answers

That's what I get.
The LCM of 21,36,66 = 2^2 * 3^2 * 7 * 11
so, you need an extra 7*11 to get a perfect square. A.
First we have to find L.C.M. of all numbers:
21=3*7
36=2*2*3*3
66=2*3*11
The L.C.M. =2*3*2*3*7*11
=2^2*3^2*7*11
For perfect square of all numbers, we need perfect square of 7and 11:
=7^2*11^2
The answer=4*9*49*121 =213444

If you want one more process for solving this question, I will help you.
Thanks