Question

which number is a perfect square? 14 18 81 90

Explanation:

Step1: Recall perfect square definition

A perfect square is a number that can be expressed as \( n^2 \), where \( n \) is an integer.

Step2: Check each number

• For 14: Find integers \( n \) such that \( n^2 = 14 \). \( 3^2 = 9 \), \( 4^2 = 16 \), so no integer \( n \) makes \( n^2 = 14 \).
• For 18: \( 4^2 = 16 \), \( 5^2 = 25 \), so no integer \( n \) makes \( n^2 = 18 \).
• For 81: \( 9^2 = 81 \), so 81 is a perfect square.
• For 90: \( 9^2 = 81 \), \( 10^2 = 100 \), so no integer \( n \) makes \( n^2 = 90 \).

Answer:

81 (from the options: the number 81, corresponding to the option with "81" as its text)