Odd One Out — For 147:741, 253:352, 518:816, 303:303, choose the pair that is not a correct reverse (or self-reverse in case of a palindrome).

Introduction / Context:
Digit reversal is a frequent theme: “abc” should map to “cba”, while palindromes map to themselves. We must identify the lone mismatch.

Given Data / Assumptions:

• Pairs shown as (left, right).
• Reversal expectation: reverse(left) = right; for palindromes, left = right.

Concept / Approach:
Reverse each left-hand number and compare with the right-hand number.

Step-by-Step Solution:
147 → reverse is 741; matches.253 → reverse is 352; matches.518 → reverse is 815; given right side is 816; does not match.303 → palindrome; reverse is 303; matches.

Verification / Alternative check:
Confirm each digit ordering explicitly to avoid off-by-one slips (815 vs 816).

Why Other Options Are Wrong:

• 147:741 — correct reversal.
• 253:352 — correct reversal.
• 303:303 — correct palindrome mapping.

Common Pitfalls:
Overlooking palindromic self-mapping or misreading “815” as “816.” Careful digit tracing prevents this.

Final Answer:
518 : 816