Odd Man Out and Series Practice Test Questions - Aptitude -- Free Practice

Question 1

Pick the odd man out:
154, 235, 352, 460, 324

A

154✓✗

B

235✓✗

C

324✓✗

D

631✓✗

Explanation

The digit sums of 154, 235, 352 and 460 are all 10, while the digit sum of 324 is 9.
So 324 is the odd number.

Question 2

W, S, Q, M, ?

A

I✓✗

B

J✓✗

C

K✓✗

D

L✓✗

Explanation

The positions of the letters are W = 23, S = 19, Q = 17, M = 13. The differences are -4, -2, -4, so the next difference is -2.
13 - 2 = 11, which is the letter K.

Question 3

1, 2, 9, 64, ?

A

125✓✗

B

625✓✗

C

225✓✗

D

525✓✗

Explanation

The terms follow the pattern n^n-1: 1⁰ = 1, 2¹ = 2, 3² = 9, 4³ = 64, and the next term is 5⁴ = 625.

Question 4

5, 25, 61, 113, ?

A

187✓✗

B

189✓✗

C

185✓✗

D

181✓✗

Explanation

The differences are 20, 36, 52, which increase by 16. The next difference = 68.
The next term = 113 + 68 = 181.

Question 5

CX, EV, GT, IR, ?

A

JQ✓✗

B

LO✓✗

C

KP✓✗

D

MN✓✗

Explanation

The first letters move forward by 2 each time: C, E, G, I, K. The second letters move backward by 2 each time: X, V, T, R, P.
The next term = KP.

Question 6

34, 45, 56, 67,78, _ ?

A

81✓✗

B

83✓✗

C

89✓✗

D

None of these✓✗

Explanation

Each term is 11 more than the previous term: 34, 45, 56, 67, 78, 89.
The next term = 78 + 11 = 89.

Question 7

FIND THE ODD NUMBER:

1,5,11,17,23,29

A

29✓✗

B

17✓✗

C

11✓✗

D

1✓✗

Explanation

The numbers 5, 11, 17, 23 and 29 are prime numbers.
1 is not a prime number, so 1 is the odd number.

Question 8

Determine the odd man out:

15, 16, 34, 105, 424, 2124

A

105✓✗

B

424✓✗

C

34✓✗

D

2124✓✗

Explanation

The series follows the pattern ×1 + 1, ×2 + 2, ×3 + 3, ×4 + 4, ×5 + 5: 15 × 1 + 1 = 16, 16 × 2 + 2 = 34, 34 × 3 + 3 = 105, 105 × 4 + 4 = 424, 424 × 5 + 5 = 2125.
So 2124 is the odd number (it should be 2125).

Question 9

Find the missing number in the series.

2 , 3 , 6 , 0 , 10, -3 , 14...

A

6✓✗

B

2✓✗

C

-2✓✗

D

-6✓✗

Explanation

The terms at the odd places are 2, 6, 10, 14, which increase by 4.
The terms at the even places are 3, 0, -3, ?, which decrease by 3.
The missing number = -3 - 3 = -6.

Question 10

Which is the odd number?

1, 8, 27, 64, 125, 196, 216, 343

A

64✓✗

B

1✓✗

C

216✓✗

D

196✓✗

Explanation

The numbers 1, 8, 27, 64, 125, 216 and 343 are the cubes of 1, 2, 3, 4, 5, 6 and 7.
196 is not a perfect cube (it is 14²), so 196 is the odd number.

Question 11

Find the odd man out.
9, 16, 25, 36, 47, 4, 81

A

25✓✗

B

47✓✗

C

4✓✗

D

81✓✗

Explanation

The numbers 9, 16, 25, 36, 4 and 81 are perfect squares (3², 4², 5², 6², 2², 9²).
47 is not a perfect square, so 47 is the odd number.

Question 12

Find out the odd number in the given sequence of numbers.
6, 12, 20, 30, 42, 54, 72, 90, 110

A

20✓✗

B

42✓✗

C

54✓✗

D

90✓✗

Explanation

The terms follow n(n + 1): 2×3 = 6, 3×4 = 12, 4×5 = 20, 5×6 = 30, 6×7 = 42, 7×8 = 56, 8×9 = 72, 9×10 = 90, 10×11 = 110.
The term at the 7th place should be 56, so 54 is the odd number.

Question 13

Find out the odd number in the given sequence of numbers.
9, 16, 25, 36, 125, 169, 196, 225

A

36✓✗

B

196✓✗

C

169✓✗

D

125✓✗

Explanation

The numbers 9, 16, 25, 36, 169, 196 and 225 are perfect squares (3², 4², 5², 6², 13², 14², 15²).
125 = 5³ is not a perfect square, so 125 is the odd number.

Question 14

Find the next number in the series: 4, 9, 20, 43, 90, ?

A

178✓✗

B

181✓✗

C

183✓✗

D

185✓✗

Explanation

The pattern is ×2 + 1, ×2 + 2, ×2 + 3, ×2 + 4, then ×2 + 5: 4 × 2 + 1 = 9, 9 × 2 + 2 = 20, 20 × 2 + 3 = 43, 43 × 2 + 4 = 90, so the next term is 90 × 2 + 5 = 185.

Question 15

Find the next number in the series: 34, 45, 56, 67, 78, ?

A

81✓✗

B

83✓✗

C

89✓✗

D

None of these✓✗

Explanation

Each term increases by 11: 78+11 = 89.

Question 16

Find the next term in the series: AYC, DVF, GSI, JPL, ?

A

KOM✓✗

B

MNO✓✗

C

OQN✓✗

D

NQO✓✗

Explanation

First letters increase by 3 (A,D,G,J -> M); second letters decrease by 3 (Y,V,S,P -> N); third letters increase by 3 (C,F,I,L -> O). Next term is MNO.

Question 17

43, 45, 51, 57, 69 -- find the odd man out among the given numbers.

A

43✓✗

B

45✓✗

C

57✓✗

D

69✓✗

Explanation

45, 51, 57 and 69 are all divisible by 3; 43 is not, making it the odd one out.

Question 18

Which pair of numbers is different from the rest? (5, 15), (6, 24), (7, 49), (9, 63)

A

(5, 15)✓✗

B

(6, 24)✓✗

C

(7, 49)✓✗

D

(9, 63)✓✗

Explanation

In (5,15), (6,24) and (9,63), the second number equals the first number multiplied by (first number - 2): 5 × 3 = 15, 6 × 4 = 24, 9 × 7 = 63. For (7,49), this rule would give 7 × 5 = 35, not 49 -- instead, 49 = 7², a different relationship. Hence (7, 49) is the odd pair out.

Question 19

Complete the following series: 3, 4, 6, 9, 13, __, __

A

17, 25✓✗

B

17, 26✓✗

C

18, 24✓✗

D

18, 25✓✗

Explanation

The differences between consecutive terms increase by 1 each time: 4-3=1, 6-4=2, 9-6=3, 13-9=4, so the next differences are 5 and 6: 13+5=18, 18+6=24.

Question 20

Complete the following series: 48, 43, 42, 37, 36, 31, 30, ..........

A

29✓✗

B

24✓✗

C

25✓✗

D

28✓✗

Explanation

The differences alternate between -5 and -1: 48 - 5 = 43, 43 - 1 = 42, 42 - 5 = 37, 37 - 1 = 36, 36 - 5 = 31, 31 - 1 = 30. Continuing the pattern, the next difference is -5: 30 - 5 = 25.

Question 21

Complete the following series: 0, 7, 26, 63, 124, ........

A

224✓✗

B

115✓✗

C

215✓✗

D

214✓✗

Explanation

Each term follows the pattern n³ - 1: 1³ - 1 = 0, 2³ - 1 = 7, 3³ - 1 = 26, 4³ - 1 = 63, 5³ - 1 = 124. Therefore, the next term = 6³ - 1 = 215.

Question 22

Find out the number that does not fit into the given series: 1, 3, 9, 27, 82

A

82✓✗

B

27✓✗

C

9✓✗

D

3✓✗

Explanation

The series represents powers of 3: 3⁰ = 1, 3¹ = 3, 3² = 9, 3³ = 27, 3⁴ = 81. The printed term 82 does not fit (it should be 81); hence 82 is the wrong number.

Question 23

Find out the number that does not fit into the given series: 54, 48, 41, 34, 24

A

54✓✗

B

48✓✗

C

41✓✗

D

34✓✗

Explanation

The differences between consecutive terms should decrease by 1 each time: 54 - 6 = 48, 48 - 7 = 41, 41 - 8 = 33, 33 - 9 = 24. The printed term 34 does not fit this pattern (it should be 33); hence 34 is the wrong number.

Question 24

Find the suitable value in place of the question mark (?): ? 42 48 54 60

A

32✓✗

B

34✓✗

C

24✓✗

D

None of these✓✗

Explanation

The series increases by a constant difference of 6: 42, 48, 54, 60 (each 6 more than the last). The preceding term must therefore be 42 - 6 = 36, which does not match any of the given numeric options; hence the answer is "None of these".

Question 25

What will come in place of the question mark (?) in the following number series? 693 697 706 722 ?

A

742✓✗

B

750✓✗

C

747✓✗

D

769✓✗

Explanation

The differences between consecutive terms are consecutive perfect squares: 697 - 693 = 4 (2²), 706 - 697 = 9 (3²), 722 - 706 = 16 (4²), so the next difference = 25 (5²). Therefore, the missing term = 722 + 25 = 747.