Write down the problem involving the square root. For instance, you might have √25 or √37.
Refer to your multiplication tables to figure out which number times itself equals the number under the radical sign. For example, 5 times 5 equals 25, so you could easily determine that √25 equals 5. The number 25 is known as a "perfect square" because a whole number times itself equals this number. If the number is fairly large, you may need to enter the number into a calculator, followed by the radical symbol (√).
Estimate the square roots for numbers that aren't perfect squares if you don't have a calculator. For example, in the case of √37, you know that 6 times 6 equals 36, and 7 times 7 equals 49. Therefore, the answer must lie just above 6. Multiply various values times themselves until you get an answer that is as precise as you need. In this case, you could multiply 6.1 times 6.1 to get 37.21. Then you could try 6.05 times 6.05 to get 36.6. After a few more tries, you could narrow your answer to 6.08.