Practice MCQ Questions and Answer on Number Series Completion
71.
What will come at the place of question mark ? 7, 26, 63, 124, 215, 342, ?
(A) 391
(B) 511
(C) 481
(D) 421
Solution:
The terms are given in a series (23 -1) = 7 (33 -1) = 26 (43 -1) = 63 (53 -1) = 124 (63 -1) = 215 (73 -1) = 342 So, the missing term is, (83 -1) = 511.
72.
In the series 3, 9, 15,.............what will be the 21st term?
(A) 117
(B) 121
(C) 123
(D) 129
Solution:
Clearly, 3 + 6 = 9, 9 + 6 = 15,.............So, the series is an A.P in which a = 3 and d = 6∴21st term = a + (21 - 1)d = a + 20d= 3 +20 × 6 = 123.
73.
J14, L16, __, P20, R22. What number should fill the blank?
(A) S24
(B) N18
(C) M18
(D) T24
Solution:
In this series, the letters progress by 2, and the numbers increase by 2.
74.
42, 40, 38, 35, 33, 31, 28, ... choose which pair of numbers comes next?
(A) 25, 22
(B) 26, 23
(C) 26, 24
(D) 25, 23
Solution:
This is an alternating subtraction series in which 2 is subtracted twice, then 3 is subtracted once, then 2 is subtracted twice, and so on.
75.
3, 8, 13, 18, 23, 28, 33, ... choose which pair of numbers comes next?
(A) 39, 44
(B) 38, 44
(C) 38, 43
(D) 37, 42
Solution:
In this simple addition series, each number is 5 greater than the previous number.
76.
3, 4, 7, 8, 11, 12, ... What number should come next?
(A) 7
(B) 10
(C) 14
(D) 15
Solution:
This alternating addition series begins with 3; then 1 is added to give 4; then 3 is added to give 7; then 1 is added, and so on.
77.
17, 32, 19, 29, 21, 26, 23, ... choose which pair of numbers comes next?
(A) 25, 25
(B) 20, 22
(C) 23, 25
(D) 25, 22
Solution:
Here, there are two alternating patterns. The first begins with 17 and adds 2; the second begins with 32 and subtracts 3.
78.
Find the missing term: 2, 3, 5, 7, 11, ?, 17
(A) 12
(B) 13
(C) 14
(D) 15
Solution:
Clearly, the given series consists of prime numbers starting from 2. So, the missing term is the prime number after 11, which is 13.
79.
2, 1, 1/2, 1/4, . . . . . . What number should come next?
(A) 1/3
(B) 1/8
(C) 2/8
(D) 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.
80.
84, 78, 72, 66, 60, 54, 48, ... choose which pair of numbers comes next?
(A) 44, 34
(B) 42, 36
(C) 42, 32
(D) 40, 34
Solution:
In this simple subtraction series, each number is 6 less than the previous number.