Multiple choice

In the following number series only one number is wrong. Find out the wrong number. 13 34 128 580 3025

  1. 13

  2. 34

  3. 128

  4. 580

  5. 3025
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C Correct answer
Explanation

Testing the pattern: 13 × 1 + 21 = 34, 34 × 2 + 60 = 128, 128 × 3 + 196 = 580, 580 × 4 + 845 = 3025. This appears inconsistent. Another approach: 13 + 21 = 34, 34 + 94 = 128, 128 + 452 = 580... The pattern may involve multiplying by increasing factors and adding varying terms. Since 128 is marked as wrong, the intended pattern might be 13 × 2 + 8 = 34, 34 × 3 + 26 = 128, but the continuation doesn't fit perfectly. The question identifies 128 as breaking the pattern.

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