Civil Service Exam Reviewer · Number Series · hard

What number(s) should complete the series: 3, 6, -1, -2, -9, -18, ?

  1. -25
  2. -36
  3. -32
  4. -27

Answer

A. -25

Solution

Alternately multiply by 2 and subtract 7: the next step is a subtraction, -18 − 7 = -25.

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