Find the next number: 6, 11, 21, 36, 56, ?
- A.76
- B.79
- C.81 ✓
- D.84
Explanation: The differences are 5, 10, 15, 20 — increasing by 5 each time. Next difference is 25, so 56+25=81.
Class 6 IMO Mathematics Olympiad practice · Patterns & Sequences · Number & Letter Sequences
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