Multiple choice

Find out the wrong number in the following series. 2.3 15.9 79.8 423 2574 18067

  1. 2.3

  2. 15.9

  3. 79.8

  4. 423

  5. 2574
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The pattern follows: ×7-0.2, ×5+0.3, ×5.5-1, ×6+0.8, ×7-1 (approximately). Checking: 2.3×7 = 16.1, but we have 15.9 (difference -0.2). 15.9×5 = 79.5+0.3 = 79.8. 79.8×5.5 = 438.9-15.9 = 423. 423×6 = 2538+36 = 2574. 2574×7 = 18018-49 = 17969, but we have 18067. The term 79.8 fits the pattern while others have inconsistencies, or 79.8 should have been calculated differently.

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