Find wrong number in series: 2, -4, 6, 8, 10, -12

Concept: In a ‘find the wrong number’ series, all the terms follow one generating rule (here, an alternating sign applied to consecutively increasing magnitudes); the wrong term is the single value that breaks that rule while everything else stays consistent.

Application:

1. The magnitudes of the given terms are 2, 4, 6, 8, 10, 12 — consecutive even numbers increasing by 2, and this holds for every term.

2. The signs of the terms should alternate: positive, negative, positive, negative, positive, negative, starting from the first term.

3. Checking the signs in order: term 1 is positive (2), term 2 is negative (-4), term 3 is positive (6), term 4 should be negative but is shown as positive (8), term 5 is positive (10), term 6 is negative (-12).

4. Term 4 is the only one that violates the alternating-sign rule — it should read -8, not 8.

Cross-check:

Re-applying the rule to every other position confirms the pattern holds everywhere else: odd positions (1st, 3rd, 5th) are positive and even positions (2nd, 4th, 6th) are negative, except at the 4th position. This isolates 8 as the wrong number.

So the wrong number in the series is 8 (it should be -8).