Multiple choice general knowledge math & puzzles

1, 3, 6, 10, 15, _______

  1. 91

  2. 81

  3. 71

  4. 41

  5. 21

  6. 31
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is a sequence of triangular numbers where the difference increases by 1 each time: +2, +3, +4, +5. The next difference is +6, so 15 + 6 = 21.

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