← General Intelligence and Reasoning

Number Series — Questions with Solutions

10 solved Number Series questions from General Intelligence and Reasoning, as asked in SSC CGL and other SSC exams. Read the answer and explanation below, then practise the full set in the practice section.

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Q1. What comes next: 5, 14, 9, 18, 13, 22, 17, ?

अगला पद क्या होगा: 5, 14, 9, 18, 13, 22, 17, ?

  1. A. 26
  2. B. 24
  3. C. 21
  4. D. 20

Solution

Alternating series: 5(+4)=9(+4)=13(+4)=17. And 14(+4)=18(+4)=22(+4)=26.

Q2. Which of the following numbers will replace the question mark (?) in the given series? 382, 322, 272, 232, 202, ?

निम्नलिखित में से कौन सी संख्या दी गई श्रृंखला में प्रश्नवाचक चिह्न (?) को प्रतिस्थापित करेगी? 382, 322, 272, 232, 202, ?

  1. A. 168
  2. B. 150
  3. C. 182
  4. D. 132

Solution

The differences between consecutive terms are -60, -50, -40, -30. The next difference will be -20. So, $202 - 20 = 182$.

Q3. The 4th term of a GP is 81 and the first term is 3. Find the common ratio.

GP का 4था पद 81 और पहला पद 3 है। सार्व अनुपात ज्ञात करें।

  1. A. 2
  2. B. 3
  3. C. 4
  4. D. 5

Solution

ar^3 = 81 => r=3.

Q4. Find the missing term in the series: ?, $132, 165, 204, 249$

श्रृंखला में लुप्त पद ज्ञात कीजिए: ?, $132, 165, 204, 249$

  1. A. 96
  2. B. 105
  3. C. 108
  4. D. 120

Solution

The differences are $165-132 = 33$, $204-165 = 39$, $249-204 = 45$. The difference is increasing by $6$. So, the first difference should be $33-6 = 27$. $132 - 27 = 105$.

Q5. Find the missing term in the series. $2, 6, 18, 54, ?$

श्रृंखला में लुप्त पद ज्ञात कीजिए: $2, 6, 18, 54, ?$

  1. A. 96
  2. B. 108
  3. C. 162
  4. D. 216

Solution

The pattern is $\times 3$. $2 \times 3 = 6$, $6 \times 3 = 18$, $18 \times 3 = 54$, $54 \times 3 = 162$.

Q6. Find the number that breaks the pattern: $3, 7, 15, 31, 63, 120$

वह संख्या ज्ञात कीजिए जो पैटर्न को तोड़ती है: $3, 7, 15, 31, 63, 120$

  1. A. 7
  2. B. 15
  3. C. 31
  4. D. 120

Solution

The pattern is $\times 2 + 1$. $3 \times 2+1=7$, $7 \times 2+1=15$, $15 \times 2+1=31$, $31 \times 2+1=63$. The next term should be $63 \times 2+1=127$, but $120$ is given.

Q7. What comes next? 5, 10, 20, 40, ?

आगे क्या आएगा? 5, 10, 20, 40, ?

  1. A. 60
  2. B. 70
  3. C. 80
  4. D. 90

Solution

The pattern is multiplying by 2. $5 \times 2 = 10$, $10 \times 2 = 20$, $20 \times 2 = 40$. Next is $40 \times 2 = 80$.

Q8. Complete the series: 3, 9, 27, 81, ?

श्रृंखला को पूरा करें: 3, 9, 27, 81, ?

  1. A. 162
  2. B. 243
  3. C. 324
  4. D. 405

Solution

The pattern is powers of 3 or multiplying by 3. $3^1, 3^2, 3^3, 3^4$. Next is $3^5 = 243$.

Q9. What comes next? 5, 10, 20, 40, ?

आगे क्या आएगा? 5, 10, 20, 40, ?

  1. A. 60
  2. B. 70
  3. C. 80
  4. D. 90

Solution

The pattern is multiplying by 2. $5 \times 2 = 10$, $10 \times 2 = 20$, $20 \times 2 = 40$. Next is $40 \times 2 = 80$.

Q10. Complete the series: 3, 9, 27, 81, ?

श्रृंखला को पूरा करें: 3, 9, 27, 81, ?

  1. A. 162
  2. B. 243
  3. C. 324
  4. D. 405

Solution

The pattern is powers of 3 or multiplying by 3. $3^1, 3^2, 3^3, 3^4$. Next is $3^5 = 243$.