You have to find which two numbers divide number 68 and one of them has a square root that is an integer. So we have : 68 = 4 * 17 ( sqrt(4)=2)
Then sqrt(68) = sqrt(4 * 17) = sqrt(4)*sqrt(17)=2 * sqrt(17) =
=2*4.123=8.246. Rounded to the nearest hundredth it is 8.25.
This id the way you can find any square using perfect square method.