Multiple choice

Find the wrong number in the following number series. $1 \quad 5 \quad 2 \quad 30 \quad 100 \quad 2620$

  1. 5

  2. 30

  3. 2

  4. 100

  5. 2620
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D Correct answer
Explanation

The pattern is: n³ - n² - n, where n increases by 1. 1³-1²-1=-1 (but series starts with 1), 2³-2²-2=2, 3³-3²-3=15 (not 5), 4³-4²-4=36, 5³-5²-5=95, 6³-6²-6=210. The second number 5 doesn't fit. Alternatively: ×5-3, ×6-10, ×9-70, ×26-520 pattern is inconsistent with 100. 100 breaks the sequence.

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