Find the least square number which is exactly divisible by 10,12,15 and 18.
L.C.M. of 10, 12, 15, 18 = 180.
Now, 180 = 2 2 3 3 5
= 22 32 5.
To make it a perfect square, it must be multiplied by 5.
Required number = (22 32 52 ) = 900.
