1. Divide the integer part of the square root into a section from the unit to the left every two digits, separate it with apostrophe, and divide it into several sections, indicating how many digits the square root is; The decimal part is separated from the highest digit to the last two digits, and the number of segments shall meet the accuracy requirements of+1.

2. According to the number in the first paragraph on the left, find the number with the highest square root.

3. Subtract the square of the highest digit from the number in the first paragraph, and write the number in the second paragraph to the right of their difference to form the first remainder.

4. Multiply the highest digit by 20 and try to divide it by the first remainder, and the largest integer is taken as the trial quotient.

5. Multiply the quotient by 20 times the highest digit of the quotient, and then multiply the quotient. If the product is less than or equal to the remainder, the quotient is the second digit of the square root; If the product obtained is greater than the remainder, try again by reducing the quotient, and the first quotient obtained is less than the remainder of the second number as the square root.

6. In the same way, continue to look for numbers on other bits of the square root. In the case of infinite openings, approximate values can be obtained according to the required accuracy. It is complicated to calculate the square root with a pen, and it is rarely used directly in practice, but the approximate value of the square root of a number with arbitrary precision can be obtained by this method.