Multiple choice general knowledge math & puzzles

Identify the wrong number in this sequence. 4,11,25,45,74,109......

  1. 74

  2. 45

  3. 11

  4. 109
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The series follows the pattern n^2 + n: 4=2^2+2, 11=3^2+2, 25=5^2+0 (doesn't fit), 45=6^2+9=45, 74=8^2+10=74, 109=10^2+9=109. The differences are: 11-4=7, 25-11=14, 45-25=20, 74-45=29, 109-74=35. Second differences: 14-7=7, 20-14=6, 29-20=9, 35-29=6. The inconsistent second differences around 25 and 45 suggest 45 or 25 is wrong. The answer key says 45 is wrong.

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