Predict the result
Simplify the square root of twenty five.
Which nonnegative number squares to twenty five?

Set up the model
The radical sign asks for the nonnegative principal square root.
Which nonnegative number squared equals twenty five?

Work the example
Five squared equals twenty five.
Five is nonnegative.
So the principal square root of twenty five is five.

Check the result
Now simplify the square root of thirty six.
Choose the nonnegative number. Take eight seconds to think.
[Eight-second silent pause to work; the answer remains hidden.]
Six squared equals thirty six.
So the principal square root of thirty six is six.

Interpret the result
Squaring the result returns the number under the radical sign.
The radical sign denotes the nonnegative principal square root.