Number sequences

What is the next number in the sequence 3, 6, 12, 24, ...?

• A36
• B42
• C48✓
• D54

Answer: Each term doubles, so 24 × 2 = 48.

What is the next number in the sequence 5, 9, 13, 17, ...?

• A19
• B20
• C21✓
• D23

Answer: The sequence increases by 4 each time, so 17 + 4 = 21.

What is the next number in the sequence 2, 5, 10, 17, 26, ...?

• A35
• B37✓
• C38
• D41

Answer: Differences are 3, 5, 7, 9, then 11; 26 + 11 = 37.

What is the missing number in the sequence 81, 27, 9, ?, 1?

• A2
• B3✓
• C4
• D6

Answer: Each term is divided by 3, so 9 ÷ 3 = 3.

What is the next number in the sequence 1, 1, 2, 3, 5, 8, ...?

• A11
• B12
• C13✓
• D15

Answer: Each term is the sum of the previous two (Fibonacci); 5 + 8 = 13.

What is the next number in the sequence 100, 92, 85, 79, 74, ...?

• A68
• B69
• C70✓
• D71

Answer: The gaps shrink by 1 each step (-8, -7, -6, -5), so the next gap is -4; 74 - 4 = 70.

What is the next number in the sequence 7, 14, 28, 56, ...?

• A84
• B98
• C112✓
• D128

Answer: Each term doubles, so 56 × 2 = 112.

What is the next number in the sequence 2, 6, 18, 54, ...?

• A108
• B144
• C162✓
• D216

Answer: Each term is multiplied by 3, so 54 × 3 = 162.

What is the next number in the sequence 1, 4, 9, 16, 25, ...?

• A30
• B32
• C36✓
• D49

Answer: These are square numbers (1², 2², 3²...); the next is 6² = 36.

What is the next number in the sequence 3, 4, 7, 11, 18, 29, ...?

• A40
• B45
• C47✓
• D48

Answer: Each term is the sum of the previous two; 18 + 29 = 47.

What is the missing number in the sequence 4, 9, 19, ?, 79?

• A29
• B39✓
• C49
• D59

Answer: Each term is double the previous plus 1; 19 × 2 + 1 = 39 (and 39 × 2 + 1 = 79).

What is the next number in the sequence 1, 2, 6, 24, 120, ...?

• A240
• B480
• C600
• D720✓

Answer: Each term is multiplied by an increasing integer (×2, ×3, ×4, ×5, then ×6); 120 × 6 = 720.