Multiple choice

Find the wrong number in the given below series. 11, 12, 26, 81, 320, 1645

  1. 11

  2. 12

  3. 81

  4. 320

  5. 26
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Pattern: ×1+1, ×2+2, ×3+3, ×4+4, ×5+5. Starting from 11: 11×1+1=12, 12×2+2=26, 26×3+3=81, 81×4+4=328 (but given 320), 328×5+5=1645. The pattern holds at all positions except the 4th term. 81×4+4=328, not 320. So 320 is incorrect.

Keep practicing — related questions