# Number Series Aptitude Q & A – Part 3

This is the Part 3 Aptitude Questions and Answers section on Number series with explanation for various interview, competitive examination and entrance test. Solved examples with detailed answer description, explanation are given and it would be easy to understand.

21. Look at this series: 201, 202, 204, 207, … What number should come next?
A. 205
B. 208
C. 210
D. 211
D. 211
Explanation:
In this addition series, 1 is added to the first number; 2 is added to the second number; 3 is added to the third number; 4 is added to the fourth number; and go on.

22. Look at this series: 544, 509, 474, 439, … What number should come next?
A. 404
B. 414
C. 420
D. 445
A. 404
Explanation:
This is a simple subtraction series. Each number is 35 less than the previous number.

23. Look at this series: 2, 1, (1/2), (1/4), … What number should come next?
A. (1/3)
B. (1/8)
C. (2/8)
D. (1/16)
B. (1/8)
Explanation:
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.

24. Look at this series: 2, 4, 6, 8, 10, … What number should come next?
A. 11
B. 12
C. 13
D. 14
B. 12
Explanation:
This is a simple addition series. Each number increases by 2.

25. 8 11 21 15 18 21 22
A. 25 18
B. 25 21
C. 25 29
D. 24 21
B. 25 21
Explanation:
This is an alternating addition series, with a random number, 21, interpolated as every third number. The addition series alternates between adding 3 and adding 4. The number 21 appears after each number arrived at by adding 3.

26. 9 16 23 30 37 44 51
A. 59 66
B. 56 62
C. 58 66
D. 58 65
D. 58 65
Explanation:
Here is a simple addition series, which begins with 9 and adds 7.

27. 84 78 72 66 60 54 48
A. 44 34
B. 42 36
C. 42 32
D. 40 34
B. 42 36
Explanation:
In this simple subtraction series, each number is 6 less than the previous number.

28. 20 20 17 17 14 14 11
A. 8 8
B. 11 11
C. 11 14
D. 11 8
D. 11 8
Explanation:
This is a simple subtraction with repetition series. It begins with 20, which is repeated, then 3 is subtracted, resulting in 17, which is repeated, and so on.

29. 14 14 26 26 38 38 50
A. 60 72
B. 50 62
C. 50 72
D. 62 62
B. 50 62
Explanation:
In this simple addition with repetition series, each number in the series repeats itself, and then increases by 12 to arrive at the next number.

30. 44 41 38 35 32 29 26
A. 24 21
B. 22 19
C. 23 19
D. 23 20
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