Classification – Odd one out (perfect squares) Three of the following numbers are perfect squares; one is not. Identify the non-square.

Introduction / Context:
Recognizing squares rapidly is essential in many number-classification tasks. The goal is to isolate the single integer that is not equal to k^2 for any integer k.

Given Data / Assumptions:

• Numbers: 1, 9, 16, 48
• We seek the non-square.

Concept / Approach:
Recall common squares: 1^2 = 1, 3^2 = 9, 4^2 = 16. Check 48 by bracketing between consecutive squares.

Step-by-Step Solution:
1 = 1^2 → square.9 = 3^2 → square.16 = 4^2 → square.48 lies between 6^2 = 36 and 7^2 = 49 → not a square.

Verification / Alternative check:
√48 ≈ 6.928… is non-integral, confirming non-square status.

Why Other Options Are Wrong:

• 1, 9, 16 → exact squares.
• None of these → there is one clear non-square (48).

Common Pitfalls:
Confusing “close to a square” with “is a square.” Only exact equality qualifies.

Final Answer:
48