Odd man out and series

(21) Which number does not belong in the series: 2, 5, 10, 17, 26, 37, 50?

• (a) 17
• (b) 26
• (c) 37
• (d) 50

Answer

Correct Answer: (a) 17
The pattern is adding consecutive prime numbers: 3, 5, 7, 11, 13, 17, 19, …
The number 17 does not fit this pattern.

(22) Look at this series: 4, 9, 16, 25, 36, 49, … What number should fill the blank?

• (a) 56
• (b) 72
• (c) 64
• (d) 64

Answer

Correct Answer: (d) 64
This is a series of perfect squares: 2^2, 3^2, 4^2, 5^2, 6^2, 7^2, \ldots
The next number should be \(8^2 = 64\).

(23) Which number does not belong in the series: 6, 14, 24, 38, 54, 74, 98?

• (a) 38
• (b) 54
• (c) 74
• (d) 98

Answer

Correct Answer: (d) 98
The pattern is adding consecutive even numbers: 6, 14, 24, 38, 54, 74, 94, …
The number 98 does not fit this pattern.

(24) Look at this series: 13, 15, 18, 22, 27, 33, … What number should fill the blank?

• (a) 37
• (b) 41
• (c) 36
• (d) 36

Answer

Correct Answer: (d) 36
The pattern is increasing numbers by consecutive integers: 13+2, 15+3, 18+4, 22+5, 27+6, 33+7, \ldots
The next number should be \(36+8 = 44\).

(25) Which number does not belong in the series: 9, 16, 25, 36, 49, 81, 100?

• (a) 25
• (b) 36
• (c) 49
• (d) 81

Answer

Correct Answer: (d) 81
This is a series of perfect squares: 3^2, 4^2, 5^2, 6^2, 7^2, 9^2, \ldots
The number 81 does not follow this pattern.