Sequence and Series

UPSC CSAT Logical Reasoning

Types of questions asked

  • Finding missing terms.
  • Find the wrong term.
  • Prime number series.
  • Addition series.
  • Subtraction series.
  • Multiplication series.
  • Division series.
  • Mixed
  • Series of series

Practice Questions

1. 4,8, , 32,64.
a. 16
b. 12
c. 18
d. 24

2. 5, 10, 23, 26, 37,50 (find the wrong term).
a. 23
b. 5
c. 37
d. 50

3. 7, 11, 13, 15, 19, 23 : find the wrong term.
a. 11
b. 13
c. 15
d. 7

4. 4,9,25,49,121,169…… : find next term.
a. 289
b. 361
c. 441
d. 529

5. 3,6,9,12,15, , 21
a. 17
b. 18
c. 19
d. 20

6. 56, 58, 62, 70, 84, 118, 182 : find the wrong term.
a. 58
b. 62
c. 84
d. 118

7. 2,6,30,210, _ , 30030 (UPSC 2012).
a. 2200
b. 2730
c. 2310
d. 2100

8. 2,10,50,260,1250,6250 : wrong term.
a. 50
b. 260
c. 1250
d. 6250

9. Look at this series: 7, 10, 8, 11, 9, 12, ... what number should come next?
a. 7
b. 10
c. 13
d. 12

10. Look at this series: 36, 34, 30, 28, 24, ... what number should come next?
a. 20
b. 22
c. 23
d. 26

11. Look at this series: 22, 21, 23, 22, 24, 23, ... what number should come next?
a. 22
b. 24
c. 25
d. 26

12. Look at this series: 80, 10, 70, 15, 60, ... what number should come next?
a. 20
b. 25
c. 30
d. 50

13. Consider the sequence given below: 4/12/95, 1/1/96, 29/1/96, 26/2/96, .... The next term of the series is (UPSC 2018)
a. 24/3/96
b. 25/3/96
c. 26/3/96
d. 27/3/96

14. What is X in the sequence 132, 129, 124, 117, 106, 93, X? (UPSC 2019)
a. 74
b. 75
c. 76
d. 77

15. What is X in the sequence 4, 196, 16, 144, 36, 100, 64, X? (UPSC 2019)
a. 48
b. 64
c. 125
d. 256

16. Consider the following sequence that follows some arrangement:
c_accaa_aa_bc_b (UPSC 2019)
The letters that appear in the gaps are

a. abba
b. cbbb
c. bbbb
d. cccc

17. Consider the following arrangement that has some missing letters:
abab_b_bcb_dcdcded_d (UPSC 2020)
The missing letters which complete the arrangement are

a. a, b, c, d
b. a, b, d, e
c. a, c, c, e
d. b, c, d, e

18. Considering the following sequence of numbers:
5 1 4 7 3 9 8 5 7 2 6 3 1 5 8 6 3 8 5 2 2 4 3 4 9 6 (UPSC 2020)
How many odd numbers are followed by the odd number in the above sequence?

a. 5
b. 6
c. 7
d. 8

19. In the series b_a_ba_b_abab_aab; fill in the six blanks () using one of the following given four choices such that the series follows a specific order. (UPSC 2021)
a. bababa
b. baabba
c. bbaabb
d. ababab

20. In the series AABABCABCDABCDE……
Which letter occupies the 100th position? (UPSC 2022)

a. H
b. I
c. J
d. K


Previous Post

Next Post