Multiple choice

In the following number series, a wrong number is given. Find out that wrong number. 2 5 21 41 122 365

  1. 2

  2. 5

  3. 21

  4. 41

  5. 122
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The series follows the pattern: term = previous term × 3 − 1, then × 2 − 1 alternately. Specifically: 2×3−1=5, 5×4+1=21 (should be 5×4+1=21), 21×2−1=41, 41×3−1=122, 122×3−1=365. Wait, let me verify: 2×3−1=5, 5×4+1=21, 21×2−1=41, 41×3−1=122. The pattern of multipliers 3, 4, 2, 3, 3 suggests 21 with multiplier 4 is incorrect. Following a 3,2,3,2 pattern, 5×2−1=9 would fit better.

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