Multiple choice

In the following number series only one number is wrong. Find out the wrong number. 2442, 1222, 614, 312, 163, 90, 56.25

  1. 1222

  2. 312

  3. 90

  4. 614

  5. 163
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The pattern is: divide by 2, then add 1, repeated. Check: 2442 ÷ 2 + 1 = 1222 ✓, 1222 ÷ 2 + 1 = 612 ✗ (given as 614). The claimed wrong number is 90, but 90 fits the pattern: 163 ÷ 2 + 1 = 82.5 (should be 82.5, not 90). Let me verify: 2442 → 1222 (÷2+1) ✓, 1222 → 614 (÷2+3? no), 614 → 312 (÷2+5), 312 → 163 (÷2+7), 163 → 90 (÷2+8.5), 90 → 56.25 (÷2+11.25). The pattern shifts. Let me recalculate: 2442 ÷ 2 = 1221, +1 = 1222 ✓. 1222 ÷ 2 = 611, +3 = 614 ✓. 614 ÷ 2 = 307, +5 = 312 ✓. 312 ÷ 2 = 156, +7 = 163 ✓. 163 ÷ 2 = 81.5, +8.5 = 90 ✓. 90 ÷ 2 = 45, +11.25 = 56.25 ✓. All numbers fit a pattern of ÷2 then add an increasing odd number. Wait—the question asks for the wrong number. Let me check if 90 breaks it: 163 ÷ 2 + 8.5 = 90, but 90 ÷ 2 + 11.25 = 56.25. The addition increments are: +1, +3, +5, +7, +8.5, +11.25. The increment from +7 to +8.5 to +11.25 is inconsistent. 90 should be 81.5 + 9 = 90.5 (if following +9). So 90 is indeed the wrong number.

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