Multiple choice

Find the wrong number in the following number series. 89, 96, 108, 120, 139, 154, 166

  1. 139

  2. 89

  3. 96

  4. 166

  5. 120
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E Correct answer
Explanation

Calculate differences: 96-89=7, 108-96=12, 120-108=12, 139-120=19, 154-139=15, 166-154=12. The pattern alternates between adding 7 and 12: 89+7=96, 96+12=108, 108+7=115, 115+12=127, etc. However, 120 breaks this pattern - it should be 115 to maintain the +7, +12 alternation. Thus 120 is the wrong number.

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