The square root of a number is a value that when multiplied by itself gives the original number. It is denoted by the symbol √. For example, the square root of 25 is 5, because 5 x 5 = 25. The square root of a negative number is not a real number, but can be represented by imaginary numbers.

To find the square root of a number, you can use a calculator or use the long division method. Here is the long division method:

1. Start by grouping the digits of the number into pairs, starting from the decimal point and working backwards. If there is only one digit left over, add a zero to make a pair.
2. Find the largest perfect square that is less than or equal to the leftmost pair of digits. Write the square root of that number above the pair.
3. Subtract the product of the square root and itself from the leftmost pair of digits, and write the remainder next to the next digit in the dividend.
4. Bring down the next pair of digits and add it to the remainder to form a new dividend.
5. Double the square root and write it next to the previous one. Then, find the largest digit to fill in the blank such that the product of the new two-digit number and the digit is less than or equal to the new dividend.
6. Subtract the product of the new two-digit number and the digit from the new dividend, and write the remainder next to the next digit in the dividend.
7. Repeat steps 5 and 6 until all the digits have been used. The final answer is the square root of the original number.