The least perfect square which is divisible by each of 21, 36 and 66 is equal to?

Ans. LCM of 21, 36 and 66 = 2772
Now, 2772 = 2 x 2 x 3 x 3 x 7 x 11
To make it a perfect square, it must be multiplied by 77 [for (7 x 11)].
∴ Required number = 2² x 3² x 7² x 11² = 213444