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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.

Read the first 6 Mensa IQ Sequence Completion flashcards as text

  1. What comes next in the sequence: 2, 6, 18, 54, ___?

    Answer: 162

    Each number is multiplied by 3 to get the next: 2×3=6, 6×3=18, 18×3=54, 54×3=162. This is a geometric sequence with a common ratio of 3.

  2. Complete the sequence: 1, 1, 2, 3, 5, 8, 13, ___?

    Answer: 21

    This is the Fibonacci sequence where each number is the sum of the two preceding numbers: 5+8=13, 8+13=21. The Fibonacci sequence appears frequently in nature and mathematics.

  3. What number completes the sequence: 3, 7, 15, 31, 63, ___?

    Answer: 127

    Each term follows the pattern: multiply by 2 and add 1. 3×2+1=7, 7×2+1=15, 15×2+1=31, 31×2+1=63, 63×2+1=127. Alternatively, these are 2^n - 1 for n = 2, 3, 4, 5, 6, 7.

  4. Complete the sequence: 1, 4, 9, 16, 25, ___?

    Answer: 36

    These are perfect squares: 1², 2², 3², 4², 5², so the next is 6² = 36. Recognizing square numbers is a fundamental pattern in IQ-type sequence problems.

  5. What comes next: 2, 3, 5, 7, 11, 13, ___?

    Answer: 17

    This is the sequence of prime numbers — numbers divisible only by 1 and themselves. After 13, the next prime is 17. The number 15 (3×5) and 16 (2⁴) are composite.

  6. Complete the sequence: 1, 8, 27, 64, 125, ___?

    Answer: 216

    These are perfect cubes: 1³, 2³, 3³, 4³, 5³, so the next is 6³ = 216. Perfect cube recognition is a key numerical reasoning skill tested in Mensa assessments.