- If a square number ends in "9", its square root is a number ending in "3" or "7".
- If a square number ends in "1", its square root is a number ending in "1" or "9".
- If a square number ends in "5", its square root is a number ending in "5" .
- If a square number ends in "4", its square root is a number ending in "2" or "8".
- If a square number ends in "6", its square root is a number ending in "4" or "6".
- If a square number ends in "0", its square root is a number ending in "0".