Yep, you can.
-5 * -5
Negative times negative gaives a positive.
5*5 = 25
So the answer would be 25
The problem with negative numbers comes when trying to find their root. Because there is no way a negative number can be multiplied by itself to give a positive number (As the negatives will always cancel each other out), it is impossible to find the root of a negative number using the real number system.
-Adam
