PlacementPrepWhat comes next in the series: 23, 38, 53, 68, 83, ?
Solution
Each term increases by 15.
83 + 15 = 98.
Answer: (D) 98
Logical Reasoning · Series and patterns
Number Series: placement practice questions
30 moderate questions in the pattern of campus placement tests. Pick an option to check your answer, then open the step-by-step solution.
What comes next in the series: 15, 21, 28, 36, 45, 55, ?
Solution
Differences between terms: 6, 7, 8, 9, 10 — they increase by 1.
Next difference = 11, so next term = 55 + 11 = 66.
Answer: (A) 66
What comes next in the series: 8, 22, 64, 190, 568, ?
Solution
Each term = previous × 3 − 2.
568 × 3 − 2 = 1702.
Answer: (D) 1702
What comes next in the series: 18, 27, 38, 51, 66, ?
Solution
The terms are squares + 2: 4²+2, 5²+2, 6²+2, 7²+2, 8²+2.
Next: 9²+2 = 83.
Answer: (D) 83
What comes next in the series: 28, 65, 126, 217, 344, ?
Solution
The terms are cubes +1: 3³, 4³, 5³, 6³, 7³, each +1.
Next: 8³+1 = 513.
Answer: (B) 513
What comes next in the series: 17, 40, 20, 36, 23, 32, ?
Solution
Two series alternate: 17, 20, 23 (adding 3) and 40, 36, 32 (subtracting 4).
The next term belongs to the first: 23 + 3 = 26.
Answer: (A) 26
Find the wrong number in the series: 13, 18, 28, 43, 63, 90, 118
Solution
The differences should be 5, 10, 15, 20, 25, 30 (increasing by 5 each time).
So the term should be 88, not 90.
Answer: (B) 90
What comes next in the series: 13, 18, 23, 28, 33, ?
Solution
Each term increases by 5.
33 + 5 = 38.
Answer: (D) 38
What comes next in the series: 5, 11, 21, 35, 53, 75, ?
Solution
Differences between terms: 6, 10, 14, 18, 22 — they increase by 4.
Next difference = 26, so next term = 75 + 26 = 101.
Answer: (A) 101
What comes next in the series: 7, 24, 75, 228, 687, ?
Solution
Each term = previous × 3 + 3.
687 × 3 + 3 = 2064.
Answer: (C) 2064
What comes next in the series: 2, 5, 10, 17, 26, ?
Solution
The terms are squares + 1: 1²+1, 2²+1, 3²+1, 4²+1, 5²+1.
Next: 6²+1 = 37.
Answer: (A) 37
What comes next in the series: 27, 64, 125, 216, 343, ?
Solution
The terms are cubes: 3³, 4³, 5³, 6³, 7³.
Next: 8³ = 512.
Answer: (B) 512
What comes next in the series: 4, 56, 6, 52, 8, 48, ?
Solution
Two series alternate: 4, 6, 8 (adding 2) and 56, 52, 48 (subtracting 4).
The next term belongs to the first: 8 + 2 = 10.
Answer: (A) 10
Find the wrong number in the series: 9, 12, 18, 25, 39, 54, 72
Solution
The differences should be 3, 6, 9, 12, 15, 18 (increasing by 3 each time).
So the term should be 27, not 25.
Answer: (B) 25
What comes next in the series: 33, 40, 47, 54, 61, ?
Solution
Each term increases by 7.
61 + 7 = 68.
Answer: (B) 68
What comes next in the series: 11, 17, 26, 38, 53, 71, ?
Solution
Differences between terms: 6, 9, 12, 15, 18 — they increase by 3.
Next difference = 21, so next term = 71 + 21 = 92.
Answer: (B) 92
What comes next in the series: 6, 19, 58, 175, 526, ?
Solution
Each term = previous × 3 + 1.
526 × 3 + 1 = 1579.
Answer: (A) 1579
What comes next in the series: 3, 8, 15, 24, 35, ?
Solution
The terms are squares − 1: 2²-1, 3²-1, 4²-1, 5²-1, 6²-1.
Next: 7²-1 = 48.
Answer: (C) 48
What comes next in the series: 125, 216, 343, 512, 729, ?
Solution
The terms are cubes: 5³, 6³, 7³, 8³, 9³.
Next: 10³ = 1000.
Answer: (D) 1000
What comes next in the series: 18, 31, 20, 29, 22, 27, ?
Solution
Two series alternate: 18, 20, 22 (adding 2) and 31, 29, 27 (subtracting 2).
The next term belongs to the first: 22 + 2 = 24.
Answer: (A) 24
Find the wrong number in the series: 10, 19, 37, 61, 100, 145, 199
Solution
The differences should be 9, 18, 27, 36, 45, 54 (increasing by 9 each time).
So the term should be 64, not 61.
Answer: (C) 61
What comes next in the series: 36, 49, 62, 75, 88, ?
Solution
Each term increases by 13.
88 + 13 = 101.
Answer: (B) 101
What comes next in the series: 17, 21, 28, 38, 51, 67, ?
Solution
Differences between terms: 4, 7, 10, 13, 16 — they increase by 3.
Next difference = 19, so next term = 67 + 19 = 86.
Answer: (B) 86
What comes next in the series: 2, 5, 11, 23, 47, ?
Solution
Each term = previous × 2 + 1.
47 × 2 + 1 = 95.
Answer: (B) 95
What comes next in the series: 25, 36, 49, 64, 81, ?
Solution
The terms are squares: 5², 6², 7², 8², 9².
Next: 10² = 100.
Answer: (A) 100
What comes next in the series: 65, 126, 217, 344, 513, ?
Solution
The terms are cubes +1: 4³, 5³, 6³, 7³, 8³, each +1.
Next: 9³+1 = 730.
Answer: (C) 730
What comes next in the series: 8, 56, 10, 54, 12, 52, ?
Solution
Two series alternate: 8, 10, 12 (adding 2) and 56, 54, 52 (subtracting 2).
The next term belongs to the first: 12 + 2 = 14.
Answer: (C) 14
Find the wrong number in the series: 17, 25, 41, 65, 101, 137, 185
Solution
The differences should be 8, 16, 24, 32, 40, 48 (increasing by 8 each time).
So the term should be 97, not 101.
Answer: (D) 101
What comes next in the series: 8, 21, 34, 47, 60, ?
Solution
Each term increases by 13.
60 + 13 = 73.
Answer: (A) 73
What comes next in the series: 16, 18, 21, 25, 30, 36, ?
Solution
Differences between terms: 2, 3, 4, 5, 6 — they increase by 1.
Next difference = 7, so next term = 36 + 7 = 43.
Answer: (C) 43
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