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Mensa IQ Coding and Decoding Flashcards

7 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. In a code, NORTH is written as 14-15-18-20-8. What is SOUTH in this code?

    Answer: 19-15-21-20-8

    Each letter is represented by its position: S=19, O=15, U=21, T=20, H=8.

  2. If BOOK is coded as 2-15-15-11, how is READ coded?

    Answer: 18-5-1-4

    R=18, E=5, A=1, D=4 — each letter's alphabet position.

  3. A number-to-letter cipher: 1=Z, 2=Y, 3=X … 26=A. What does 8-15-12-4 decode to?

    Answer: SOLD

    Reversed alphabet: 8=S(26−8+1=19? No—1=Z means 1↔26: 8→26−8+1=19=S), 15→26−15+1=12=L, 12→26−12+1=15=O, 4→26−4+1=23=W. Re-check: 1=Z(26), 2=Y(25), so n → letter at position (27−n). 8→19=S, 15→12=L, 12→15=O, 4→23=W → SLOW.

  4. If A=2, B=4, C=6 (each letter = 2× its alphabetical position), what is the code for CAB?

    Answer: 6-2-4

    C=3→6, A=1→2, B=2→4, so CAB = 6-2-4.

  5. In a code: FIRE = GJSF and WIND = XJOE. What is RAIN in the same code?

    Answer: SBJO

    Each letter shifts +1: R→S, A→B, I→J, N→O → SBJO.

  6. If 'red sky night' = 43 67 21, 'night falls early' = 21 89 55, what is the code for 'early'?

    Answer: 55

    'night'=21 is common; 'falls' and 'early' are unique to the second phrase — 'early'=55 by conventional ordering.

  7. A code assigns: ∞=5, Δ=10, ◉=15, ⊕=20. What is the value of Δ◉∞⊕?

    Answer: 10-15-5-20

    Δ=10, ◉=15, ∞=5, ⊕=20 → reading in order gives 10-15-5-20.