Civil Service Exam Reviewer · Number Series · hard

What number(s) should complete the series: 10, 20, 13, 26, 19, 38, ?

  1. 76
  2. 24
  3. 57
  4. 31

Answer

D. 31

Solution

Alternately multiply by 2 and subtract 7: the next step is a subtraction, 38 − 7 = 31.

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