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Mensa IQ Sequence Completion Flashcards

6 cards from real MENSA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. What number comes next: 0, 1, 3, 6, 10, 15, ___?

    Answer: 21

    These are triangular numbers. The differences between consecutive terms are 1, 2, 3, 4, 5, 6. The next difference is 6, so 15 + 6 = 21. Triangular numbers equal n(n+1)/2.

  2. Complete the sequence: 256, 128, 64, 32, ___?

    Answer: 16

    Each number is divided by 2 (or halved): 256/2=128, 128/2=64, 64/2=32, 32/2=16. These are descending powers of 2: 2⁸, 2⁷, 2⁶, 2⁵, 2⁴.

  3. What comes next in the sequence: 2, 5, 10, 17, 26, ___?

    Answer: 37

    The differences between terms are 3, 5, 7, 9 — increasing by 2 each time. The next difference is 11, so 26 + 11 = 37. This is also n² + 1 for n = 1, 2, 3, 4, 5, 6.

  4. Complete the sequence: 1, 2, 4, 7, 11, 16, ___?

    Answer: 22

    The differences between consecutive terms are 1, 2, 3, 4, 5 — increasing by 1 each time. The next difference is 6, so 16 + 6 = 22. This accelerating pattern tests recognition of second-order sequences.

  5. What number replaces the question mark: 3, 6, 12, 24, 48, ___?

    Answer: 96

    Each number is doubled: 3×2=6, 6×2=12, 12×2=24, 24×2=48, 48×2=96. This is a straightforward geometric sequence with common ratio 2.

  6. Complete the sequence: 1, 3, 6, 10, 15, 21, 28, ___?

    Answer: 36

    These are triangular numbers. Each term adds the next natural number: +2, +3, +4, +5, +6, +7, +8. The next term is 28 + 8 = 36. The formula is n(n+1)/2.