Direction: In the following number series, a wrong number is given. Find out that wrong number.
1. 3.2, 4.8, 2.4, 3.6, ?, 2.7

A. 12.5 B. 1.8 C. 6.8 D. 13.2

Answer - Option B
Explanation -
The series is
3.2 × 1.5= 4.8
4.8 ÷ 2= 2.4
2.4 × 1.5= 3.6
3.6 ÷ 2= 1.8
2. 5, 6, 14, 45, ?, 925, 5556

A. 194 B. 184 C. 202 D. 143

Answer - Option B
Explanation -
The pattern of the series can be judged by the logical sequence given below:
5 × 1 + 1 = 6
6 × 2 + 2 = 14
14 × 3 + 3 = 45
45 × 4 + 4 = 184
184 × 5 + 5 = 925
92 × 6 + 6 = 5556
Key note: Multiple operations i.e. (×,+), (×,-), (÷,+), (÷, -) are majorly used in the number series questions.
3. 1, 5, 9, 17, 25, ?

A. 35 B. 37 C. 25 D. 28

Answer - Option B
Explanation -
[latex]{1}^{2}[/latex] = 1
[latex]{2}^{2}[/latex] + 1 = 5
[latex]{3}^{2}[/latex] = 9
[latex]{4}^{2}[/latex] + 1 = 17
[latex]{5}^{2}[/latex] = 25
[latex]{6}^{2}[/latex] + 1 = 37
4. 2, 4, 10, 32, ?, 652

A. 130 B. 150 C. 170 D. 190

Answer - Option A
Explanation -
The pattern followed is: 2, 4, 10, 32, ?, 652
4 = 2 × 1 + 2
10 = 4 × 2 + 2
32 = 10 × 3 + 2
? = 32 × 4 + 2, i.e. ? = 130
652 = 130 × 5 + 2
5. 1, 9, 36, 100, 225, ?

A. 441 B. 484 C. 400 D. 289

Answer - Option A
Explanation -
1, 9, 36, 100, 225, (441)
[latex]{1}^{2}, {3}^{2}, {6}^{2}, {10}^{2}, {15}^{2}, {21}^{2} [/latex]
(3 – 1) = 2
(6 – 3) = 3
(10 – 6) = 4
(15 – 10) = 5
(X – 15) = 6
X = 21
Required term = [latex]{21}^{2}[/latex] = 441

Direction: In the following number series, a wrong number is given. Find out that wrong number.
1. 14, 9, 20, 12 , ?, 15

A. 55 B. 14 C. 30 D. 26

Answer - Option D
Explanation -
14 ÷ 2 + 2 = 9
9 × 2 + 2 = 20
20 ÷ 2 + 2 = 12
12 × 2 + 2 = 26
26 ÷ 2 + 2 = 15
2. 142, 143, 156, 193, 272, 417, ?

A. 653 B. 658 C. 659 D. 657

Answer - Option B
Explanation -
The difference between numbers is [latex]+ {1}^{3} + 0, + {2}^{3} + 5,+ {3}^{3} + 10 , +{4}^{3} + 15, + {5}^{3} + 20, + {6}^{3} + 25[/latex]
3. 8544, 1420, ?, 66, 18, 5

A. 862 B. 548 C. 495 D. 280

Answer - Option D
Explanation -
8544 (÷ 6 - 4), 1420 (÷ 5 - 4) 280 (÷ 4 - 4) 66 (÷ 3 - 4) 18 (÷ 2 - 4) 5
4. 9, 19, 59, ?, 1199, 7199

A. 319 B. 279 C. 259 D. 239

Answer - Option D
Explanation -
9,
19 = 9 × 2 + 1,
59 = 19 × 3 + 2,
Thus,? = 59 × 4 + 3 = 239,
1199 = 239 × 5 + 4
7199 = 1199 × 6 + 5
239 is the missing number.
5. 7, 14, 23, 34, ?, 62

A. 47 B. 55 C. 49 D. 52

Answer - Option A
Explanation -

Direction: In the following number series, a wrong number is given. Find out that wrong number.
1. 25, 21, 48, 30, 157, 121

A. 25 B. 157 C. 21 D. 30

Answer - Option D
Explanation -
25, 21, 48, (32), 157, 121
The Pattern is:-
→ 25
→ 21 = 25 - [latex]{2}^{2}[/latex]
→ 48 = 21 + [latex]{3}^{3}[/latex]
→ 32 = 48 - [latex]{4}^{2}[/latex]
→ 157= 32 + [latex]{5}^{3}[/latex]
→ 121= 157 - [latex]{6}^{2}[/latex]
2. 100, 101, 97, 106, 92, 115, 79

A. 101 B. 97 C. 92 D. 115

Answer - Option C
3. 4, 15, 41, 130, 378, 1141, 3415

A. 4 B. 41 C. 378 D. 130

Answer - Option D
Explanation -
The series is 4 [latex]\times[/latex] + 3 = 15
15 [latex]\times[/latex] 3 - 4 = 41
41 [latex]\times[/latex] 3 + 5 = 128
128 [latex]\times[/latex] 3 - 6 = 378
378 [latex]\times[/latex] 3 + 7 = 1141
1141 [latex]\times[/latex] 3 - 8 = 3415
Hence, there should be 128 in place of 130.
4. 1, 5, 19, 77, 307, ?

A. 1265 B. 1266 C. 1229 D. 1270

Answer - Option C
Explanation -
The given series is
5 = 1 [latex]\times[/latex] 4 + 1
19 = 5 [latex]\times[/latex] 4 -1
77 = 19 [latex]\times[/latex] 4 + 1
307 = 77 [latex]\times[/latex] 4 - 1
1229 = 307 [latex]\times[/latex] 4 + 1
5. 20, 19, 17, ?, 10, 5

A. 14 B. 13 C. 15 D. 12

Answer - Option A
Explanation -
Difference -1, -2, -3, -4 & so on