To find the greatest perfect square that is a factor of 756, we first find the factors of 756. Factors of 756 are: 1,2,3,4,6,7,9,12,14,18,21,27,28,36,42,54,63,84,108,126,189,252,378,756 Now we start to find the perfect square from the greatest factors; 756 = not perfect square 378 = not perfect square 252 = not perfect square 189 = not perfect square 126 =not perfect square 108 =not perfect square 84 = not perfect square 63 = not perfect square 54 = not perfect square 42 = not perfect square 36 = perfect square = 6 x 6 = 6² = 36 So, 36 is the greatest perfect square from the factors of 756.