Classification – Odd one out (number strings): Identify the number string that does not follow the same construction: 67626, 84129, 32418, 47632.

Introduction / Context:
Odd-one-out questions on number strings often hide a specific concatenation rule. A very common device is to append a key value (like n) to a function of that value (like n^2), producing a recognizable pattern in several items. The goal is to spot the single member that breaks the rule.

Given Data / Assumptions:

• Candidates: 67626, 84129, 32418, 47632.
• Assume base-10 strings that may represent concatenations.

Concept / Approach:
Test if the first part is a perfect square of the tail part. Specifically, check whether each string equals n^2 concatenated with n for some integer n. If three follow that exact blueprint and one does not, the nonconforming string is the outlier.

Step-by-Step Solution:
67626 → split as 676 | 26. Since 26^2 = 676, this matches the pattern n^2 || n with n = 26.84129 → 841 | 29. Since 29^2 = 841, this matches with n = 29.32418 → 324 | 18. Since 18^2 = 324, this matches with n = 18.47632 → trying 476 | 32 gives 32^2 = 1024, not 476; no obvious n fits the n^2 || n form.

Verification / Alternative check:
Attempting different splits of 47632 (e.g., 47|632 or 4|7632) does not yield an integer n with n^2 concatenated to n. Therefore, 47632 uniquely fails the rule that the others satisfy.

Why Other Options Are Wrong:

• 67626, 84129, 32418 all perfectly implement n^2 followed by n.

Common Pitfalls:
Assuming arithmetic operations rather than concatenation can mask the simple structure. Always test concatenation patterns early in such puzzles.

Final Answer:
47632