To find the greatest perfect square that is a factor of 396, first we check what are the factors of 396
Factors of 396 are: 1,2,3,4,6,9,11,12,18,22,33,36,44,66,99,132,198,396
Now we check which is the greatest perfect square in these.
396, 198, 132, 99, 66,44 are not perfect square,
so 36 is the largest perfect square from the factors of 396, 6 x 6 = 6² = 36
