Which of the following numbers is NOT a perfect square?
Show answer & explanation
Correct answer: D
Explanation
Given:
Options: 900, 441, 729, 640
Perfect square = n²
900 = 30² (perfect square)
441 = 21² (perfect square)
729 = 27² (perfect square)
640 = between 25² = 625 and 26² = 676, so it is not a perfect square.