Number Series Questions For IBM

Q2.Look at this series: 80, 10, 70, 15, 60, ... What number should come next?

• 20
• 25
• 30
• 50

Solution:-A

here 1,3,5............... terms are  decreasing by 10

and 2,4,6,8................ are being increased by 5

so 6th term = 15 5=20;

Q3.Find the number that can be put in place of the question mark.
3 7 14 23 36 49 ? 83 104

• 66
• 56
• 110
• 62

Solution:-B

7-3=4 4*4=16 16-2=14
36-23=13 13*4=52 52-3=49
83-56=27 27*4=108 108-4=104

Q4.Find the wrong number in the given series.3, 4, 10, 32, 136, 685, 4116

• 10
• 32
• 136
• 4116

Solution:-The sequence is as follows :

2nd term = (1st term 1) * 1

3rd term = (2nd term 1) * 2

4th term = (3rd term 1) * 3 and so on.

So, 32 is wrong and must be replaced by (10 1) * 3Â i.e. 33.

Q5. 1.5, 2.3, 3.1, ?, 4.7

• 3.2
• 3.4
• 3.7
• 3.9

Solution:-D. 3.9

However, In this simple addition series, each number increases by 0.8.

Q6.Find the number that can be put in place of the question mark.?

8,5,9,7,2,25,5,1,16,8,6,?

• 2
• 4
• 5
• 1

Solution:-B

8-5=3 ->3^2=9

7-2=5 ->5^2=25

5-1=4 ->4^2=16

8-6=2 ->2^2=4

Q7. Find the wrong number in the given sequence
31, 2, 41, 3, 52, 4, 61, 5, 71, 6

• 41
• 61
• 52
• 31

Solution:- C

In this sequence, there is a combination of two given series:
I. 31, 41, 52, 61, 71 and II. 2, 3, 4, 5, 6
Here, the pattern in I is + 10
Therefore, 52 is wrong and should be replaced by the previous number 41+10 = 51.

Q8. 15 , 22, 72, 552 , ?

• 8800
• 4763
• 4500
• 4592

Solution:- A.8800

15×2 – 8 = 22
22×4 – 16 = 72
72×8 – 24 = 552
552×16 – 32 = 8800

Q9. 69, 77.28, 86.55, 96.936, ?

• 102.546
• 108.568
• 105.675
• 119.876

Solution:-B

69 + (12*69/100) = 69 + 8.28 = 77.28
77.28 + (12*77.28/100) = 77.28 + 9.27 = 86.55
86.55 + (12*86.55/100) = 86.55 +10.386 = 96.936
96.936 + 11.632 = 108.568

Q10. 10 16.5 43.75 156.625 ?

• 709.3125
• 809.3125
• 699.3125
• 609.3125
• None of these

Solution-A

10*1.5 + 1.5 = 16.5
16.5*2.5 + 2.5 = 43.75
43.75*3.5 + 3.5 = 156.625
156.625*4.5 + 4.5 = 709.3125

Q11.Look at this series: 2, 1, (1/2), (1/4), ... What number should come next?

• 1/3
• 1/8
• 2/8
• 1/16

Solution:-This is a simple division series; each number is one-half of the previous number. In other terms to say, the number is divided by 2 successively to get the next result.

4/2 = 2

2/2 = 1

1/2 = 1/2

(1/2)/2 = 1/4

(1/4)/2 = 1/8 and so on.

Q12.Look at this series: 53, 53, 40, 40, 27, 27, ... What number should come next?

• 12
• 14
• 27
• 53

Solution:-B

In this series, each number is repeated, then 13 is subtracted to arrive at the next number.

Q13. 3, 12, 8, 19, 13, 32, 18, 42, 23, 52 

• 12
• 19
• 42
• 32
• None of the above

Solution:-B

The sequence is a combination of following two series:
I. 3, 8, 13, 18, 23 and II. 12, 19, 32, 42, 52
The pattern in I has a constant difference of +5, and the pattern in II has a constant difference of +10. So, in II, 19 is wrong and should be replaced by (12+10) i.e. 22

Q14. 1, 125, 729, 2177 

• 2177
• 729
• 125
• 1
• 121

Solution:-A

1, 125, 729, 2177
1 = 1³ , 125 = 5³, 729 = 9³. So, next number would be 13³= 2197
Therefore, 2177 is wrong.

Q15. 21, 35, 56, 91, 154, ?

• 273
• 289
• 231
• 240
• 245

Solution:- A

21 × 2 – 7 = 35
35 × 2 – 14 = 56
56 × 2 – 21 = 91
91 × 2 – 28 = 154
154 × 2 – 35 = 273

Q16. 5, 7, 25, 131, ?, 8335

• 865
• 914
• 1025
• 802
• 925

Solution:- E

5 × 1 + 2 = 7
7 × 3 + 4 = 25
25 × 5 + 6 = 131
131 × 7 + 8 = 925
925 × 9 + 10 = 8335

Q17. 5, 8, 28, 162, ?, 12870

• 1738
• 2318
• 2224
• 2950
• 1288

Solution:- C

×2 – 2, ×4 – 4, ×6 – 6, ×8 – 8, ×10 – 10.

Q18. 11, 6, 5, 9, 16, ?

• 66.5
• 78.5
• 89.5
• 42.5
• 31.5

Solution:- D

11 ×0.5 + 0.5 = 6
6 ×1 – 1 = 5
5 ×1.5 + 1.5 = 9
9 ×1 – 1 = 16
16 ×2.5 + 2.5 = 42.5

Q19. 17.5 31 58 98.5 152.5

• 180.5
• 220
• 205
• None of these
• 169.5

Solution:- C

Q20. 2 13 27 113 561 3369 23581

• 3
• 39
• 11
• 20
• 6

Solution:- C