A simple yet surprisingly efficient method to calculate the square root of a number is variously called Heron’s method, Newton’s method, or the divideand-average method. To find the square root of the number a:

1. Begin with an initial estimate x. 2. Divide the number by the estimate (i.e., evaluate dx), to get a new 3. Average the original estimate and the new estimate (i.e., (x + dx)/2) estimate to get a new estimate

4. Return to step 2. Use this method to calculate the square root of a number. The value of the initial estimate x must be greater than zero.