Find the next number in the series: 2, 5, 10, 17, 26, ?

  • A. 35
  • B. 37
  • C. 39
  • D. 41

Explanation

The differences are 3, 5, 7 and 9, rising by 2 each time, so the next difference is 11 and the next term is 26 plus 11, which is 37. The same series can be read as n squared plus 1 for n equal to 1, 2, 3 and so on, which gives 36 plus 1 for the sixth term. When first differences are not constant, always take the second differences.

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