Mensa IQ Numerical Reasoning and Arithmetic Flashcards

What is the missing number? 7, 14, 28, 56, [?], 224

Answer: 112

Each term doubles; 56 × 2 = 112.

In a 3×3 magic square, each row, column, and diagonal sums to the same magic constant. Given top row: 2, 7, 6; middle row: 9, 5, 1; what is the sum of the bottom row?

Answer: 15

The magic constant for this square is 15 (each row, column, diagonal); bottom row = 4, 3, 8 sums to 15.

A sequence: 4, 9, 16, 25, 36, [?]

Answer: 49

These are perfect squares of consecutive integers starting at 2: 2², 3², 4², 5², 6², 7² = 49.

A factory produces 240 units in 8 hours with 6 workers. How many units do 9 workers produce in 10 hours at the same rate?

Answer: 450

Rate = 240/(8×6) = 5 units per worker per hour; 9 workers × 10 hours × 5 = 450.

What value replaces [?] in the sequence: 1, 3, 7, 15, 31, [?]?

Answer: 63

Each term = 2 × previous + 1; or equivalently each term = 2ⁿ − 1: 1, 3, 7, 15, 31, 63.

Three numbers are in ratio 2:3:5. Their sum is 150. What is the largest of the three numbers?

Answer: 75

Total parts = 2+3+5 = 10; each part = 150/10 = 15; largest (5 parts) = 5×15 = 75.

A number sequence alternates between adding and multiplying: 1, +3→4, ×2→8, +3→11, ×2→22, +3→[?]

Answer: 25

The rule alternates: add 3, multiply by 2. After 22+3 = 25.