CRE 1 - Number Series | LR - Series
What should come in place of question mark (?) in the following number series?
5, 9, 15, 23, ?
- A.
33
- B.
36
- C.
35
- D.
37
- E.
34
Answer: Option A
Explanation :
Here the series follows as, +4, +6, +8 and so on. So, the missing number will be 23 + 10 = 33.
Hence, option (a).
Workspace:
2, 8, 18, 32, ?
- A.
48
- B.
49
- C.
51
- D.
50
- E.
46
Answer: Option D
Explanation :
Here the next numbers are generated as + 6, + 10, + 14 and now it has to be + 18 and the next number will be 32 + 18 = 50.
Hence, option (d).
Workspace:
5, 17, 37, 65, 101, ?
- A.
122
- B.
143
- C.
145
- D.
121
Answer: Option C
Explanation :
Here the series follows as 22 + 1, 42 + 1, 62 + 1, and so on. So, the term will be 122 + 1 = 145.
Hence, option (c).
Workspace:
12, 17, 24, 33, ?
- A.
46
- B.
44
- C.
39
- D.
37
Answer: Option B
Explanation :
Here the series follows as +5, +7, +9, +11 and so on. So, the term will be 33 + 11 = 44.
Hence, option (b).
Workspace:
2, 2, 4, 12, 48, ?
Answer: 240
Explanation :
Here the series follows as × 1, × 2, × 3, × 4 and so on.
So, the next term will be 48 × 5 = 240.
Hence, 240.
Workspace:
1, 3, 6, 18, 36, ?
- A.
52
- B.
108
- C.
76
- D.
85
Answer: Option B
Explanation :
Here the series follows as × 3, × 2, × 3, × 2 and so on.
So, the term will be 36 × 3 = 108
Hence, option (b).
Workspace:
10, 15, 25, 35, 55, ?
- A.
65
- B.
75
- C.
85
- D.
90
Answer: Option A
Explanation :
Here each number is written as the product of 5 and a prime number i.e. 5 × 2, 5 × 3, 5 × 5, 5 × 7, 5 × 11 and so on.
So, the next term will be 5 × 13 = 65.
Hence, option (a).
Workspace:
5, 7, 10, 13, 17, 19, ?
- A.
20
- B.
25
- C.
26
- D.
None of these
Answer: Option C
Explanation :
The given sequence is the combination of two series
I ⇒ 5, 10, 17
II ⇒ 7, 13, 19
In the first series, +5, +7, +9 follows and in second series, +6 follows
So, the next term will be 17 + 9 = 26.
Hence, option (c).
Workspace:
510, 490, 472, 456, 442, ?
- A.
433
- B.
428
- C.
421
- D.
430
Answer: Option D
Explanation :
Here the series follows as -20, -18, -16, -14 -12 and so on.
So, the next term will be 442 – 12 = 430.
Hence, option (d).
Workspace:
7, 15, 31, 63, ?
Answer: 127
Explanation :
Here the series can be written as (7 × 2 + 1), (15 × 2 + 1), (31 × 2 + 1) and so on.
So, the next term will be (63 × 2 + 1) = 127.
Hence, 127.
Workspace:
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