Question: how to work out the square root of a large number without a calculator?
Answer: Examples. Finding square roots of of numbers that aren't perfect squares without a calculator. Example: Calculate the square root of 10 ( ) to 2 decimal places. Find the two perfect square numbers it lies between. Divide 10 by 3. ...  Average 3.33 and 3. ( ...  Repeat step 2: 10/3.1667 = 3.1579.