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UPSC CSE 2026 · PYQ · Number Series · easy

In a sequence of numbers, except for the first two numbers, every number is the sum of its exactly two predecessor numbers. If the first two numbers in this sequence are 4 and 7, then what is the sixth number?

  1. A.29
  2. B.37
  3. C.43
  4. D.47✓ Correct

Explanation

Sequence: a1 = 4, a2 = 7. a3 = 4 + 7 = 11. a4 = 7 + 11 = 18. a5 = 11 + 18 = 29. a6 = 18 + 29 = 47. The sixth number is 47.
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