Number series (find the wrong term): 25, 36, 49, 81, 121, 169, 225

Introduction / Context:
This is a squares-based series. All terms are perfect squares of odd numbers in ascending order — except one even square that slips in erroneously. Identifying it requires recognizing the odd-square pattern.

Given Data / Assumptions:

• Series: 25, 36, 49, 81, 121, 169, 225.
• Exactly one term is wrong.

Concept / Approach:
List the square roots: 5, 6, 7, 9, 11, 13, 15. All are odd except 6. The intended pattern is consecutive odd integers squared (5^2, 7^2, 9^2, 11^2, 13^2, 15^2).

Step-by-Step Solution:
25 = 5^2 (odd).36 = 6^2 (even) → suspicious.49 = 7^2 (odd), 81 = 9^2 (odd), 121 = 11^2 (odd), 169 = 13^2 (odd), 225 = 15^2 (odd).Therefore, 36 is the only even square intruding in a run of odd squares.

Verification / Alternative check:
Removing 36 gives a clean sequence of squares of consecutive odd numbers: 5, 7, 9, 11, 13, 15.

Why Other Options Are Wrong:

• 49, 121, 169, 225 are all odd squares; each supports the intended structure.

Common Pitfalls:

• Assuming all squares in order, missing that the rule is specifically odd squares.

Final Answer:
36