Square number: If any natural number m can be expressed as n2, where n is also a natural number, then m is known as a square number. The square numbers are also called as perfect squares. A Square root of a number is a value that, when multiplied by itself, gives the number. Example: 4 × 4 = 16, so a square root of 16 is 4. The square root is the number that when multiplied by itself equals that value. For instance, the square root of 4 is 2 because 2 times itself is 4. 4 is a perfect square. A perfect square is a value that has a whole number square root. While finding the square roots, positive number has two square roots; a positive (called the principal square root) and a negative. All square numbers end with 0, 1, 4, 5, 6 or 9 at unit’s place. Square numbers can only have even number of zeros at the end.