Reasoning — Number Series

8 mins
Time
10
Questions
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1
Per Q

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Reasoning — Number Series — Questions with Answers Open after you finish the quiz — all 10 questions, with answers and explanations.
Q1. Find the next number in the series: 12, 19, 26, 33, ?
  1. 38
  2. 40
  3. 42
  4. 44
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Answer: B. 40
The pattern in the series is adding 7 to the previous number. 12 + 7 = 19 19 + 7 = 26 26 + 7 = 33 Following this pattern, the next number will be 33 + 7 = 40.
Q2. Find the next number in the series: 3, 9, 27, 81, ?
  1. 162
  2. 216
  3. 243
  4. 270
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Answer: C. 243
The pattern in the series is multiplying the previous number by 3. 3 * 3 = 9 9 * 3 = 27 27 * 3 = 81 Following this pattern, the next number will be 81 * 3 = 243.
Q3. Find the next number in the series: 5, 12, 26, 54, ?
  1. 108
  2. 110
  3. 112
  4. 114
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Answer: B. 110
Let's find the differences between consecutive terms: 12 - 5 = 7 26 - 12 = 14 54 - 26 = 28 The differences are 7, 14, 28. This is a geometric progression where each difference is multiplied by 2. So, the next difference will be 28 * 2 = 56. Adding this to the last term: 54 + 56 = 110.
Q4. Find the next number in the series: 1, 8, 27, 64, ?
  1. 100
  2. 121
  3. 125
  4. 130
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Answer: C. 125
The pattern in the series is the cube of consecutive natural numbers. 1 = 1^3 8 = 2^3 27 = 3^3 64 = 4^3 Following this pattern, the next number will be 5^3 = 125.
Q5. Find the next number in the series: 4, 9, 20, 43, ?
  1. 88
  2. 89
  3. 90
  4. 91
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Answer: C. 90
The pattern in the series is (previous number * 2) + an increasing natural number starting from 1. 4 * 2 + 1 = 9 9 * 2 + 2 = 20 20 * 2 + 3 = 43 Following this pattern, the next number will be 43 * 2 + 4 = 86 + 4 = 90.
Q6. Find the next number in the series: 7, 10, 16, 28, ?
  1. 48
  2. 50
  3. 52
  4. 54
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Answer: C. 52
Let's find the differences between consecutive terms (First difference): 10 - 7 = 3 16 - 10 = 6 28 - 16 = 12 The first differences are 3, 6, 12. Now, let's find the differences between these first differences (Second difference): 6 - 3 = 3 12 - 6 = 6 The second differences are 3, 6. This indicates a pattern of multiplying by 2. So, the next second difference will be 6 * 2 = 12. The next first difference will be 12 + 12 = 24. Adding this to the last term: 28 + 24 = 52.
Q7. Find the next number in the series: 2, 5, 10, 17, 26, ?
  1. 35
  2. 36
  3. 37
  4. 38
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Answer: C. 37
The pattern in the series is n^2 + 1, where n is the position of the term starting from 1. 1^2 + 1 = 1 + 1 = 2 2^2 + 1 = 4 + 1 = 5 3^2 + 1 = 9 + 1 = 10 4^2 + 1 = 16 + 1 = 17 5^2 + 1 = 25 + 1 = 26 Following this pattern, the next number (6th term) will be 6^2 + 1 = 36 + 1 = 37.
Q8. Find the next number in the series: 2, 3, 5, 7, 11, ?
  1. 12
  2. 13
  3. 14
  4. 15
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Answer: B. 13
The series consists of prime numbers in ascending order. 2, 3, 5, 7, 11 are the first five prime numbers. The next prime number after 11 is 13.
Q9. Find the next number in the series: 1, 1, 2, 3, 5, 8, ?
  1. 11
  2. 12
  3. 13
  4. 14
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Answer: C. 13
This is a Fibonacci series, where each number is the sum of the two preceding ones. 1 + 1 = 2 1 + 2 = 3 2 + 3 = 5 3 + 5 = 8 Following this pattern, the next number will be 5 + 8 = 13.
Q10. Find the next number in the series: 100, 99, 95, 86, 70, ?
  1. 40
  2. 45
  3. 50
  4. 55
Show answer
Answer: B. 45
Let's find the differences between consecutive terms: 99 - 100 = -1 95 - 99 = -4 86 - 95 = -9 70 - 86 = -16 The differences are -1, -4, -9, -16. These are the negative squares of consecutive natural numbers: -1 = -(1^2) -4 = -(2^2) -9 = -(3^2) -16 = -(4^2) Following this pattern, the next difference will be -(5^2) = -25. Subtracting this from the last term: 70 - 25 = 45.
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