What is the square root of 625 simplified in radical form?
Also, let's not forget that -25 works too!
If no calculator to hand it is always worth trying this type of trick
Consider the last digit of 625
This is 5. So the first question is, what times itself give the last digit of 5.
Consider the hundreds ie 600
Putting this together lets test
If all else fails and you do not have a calculator to hand build a prime factor tree.
From this observe that we have