Multiple choice

Which number is wrong in the given series? 2, 12, 30, 54, 90

  1. 2

  2. 30

  3. 54

  4. 12
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The pattern is n² + n for n = 1, 2, 3, 4, 5...: 1²+1=2, 2²+2=6, 3²+3=12, 4²+4=20, 5²+5=30, 6²+6=42, 7²+7=56, 8²+8=72, 9²+9=90. The given series is: 2 (correct), 12 (correct), 30 (correct), 54 (wrong - should be 42), 90 (wrong position). The number 54 breaks the pattern.

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