Reasoning & Mental Aptitudeseriesmedium

Number and Letter Series Quiz

Free practice quiz on Number and Letter Series Quiz with detailed solutions for government exam preparation.

25
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About This Quiz

Number and Letter Series Quiz is a free, 25-minute, 25-mark practice quiz on AajExam rated at medium difficulty, designed to help candidates preparing for SSC, UPSC, Banking, Railway and State PSC government competitive exams sharpen their command of series (Reasoning & Mental Aptitude). Every question on this quiz ships with a detailed step-by-step solution so you don't just learn the right answer — you learn the reasoning and shortcuts top scorers use to crack similar questions faster on the actual exam day. Why Number and Letter Series Quiz matters in your preparation: government exam-conducting bodies repeatedly draw questions from the same chapters and the same skill-clusters across recruitment cycles. By attempting focused topic-wise quizzes like this one, you build pattern recognition — the ability to spot which formula, rule or trick applies the moment you see a question. Toppers consistently report that 5-10 quizzes on a single topic delivers more exam-day score gain than 20+ unfocused full-length mocks, because targeted drilling exposes your specific sub-topic weaknesses with surgical precision. How to use this quiz effectively: attempt it in one sitting under the 25-minute timer, without referring to notes or external resources — simulate exam-day conditions exactly. After submission, review the auto-generated analytics to see your accuracy, time per question and section-wise performance. Then go through every wrong and skipped question with the explanation, mentally tagging the underlying concept rather than just memorising the answer. Revisit this quiz after 7-10 days; your second attempt should be 15-20% faster with noticeably better accuracy. Bookmark this page and revisit weekly as we add new quizzes on related topics. AajExam quiz design principles: every quiz on the platform is curated by subject experts using the actual question formats, difficulty distributions and time pressures of the target government exams. We deliberately avoid generic "textbook" questions in favour of exam-replicating ones. Solutions are written in plain English (and Hindi where source material was bilingual), with step-by-step working for quantitative problems, grammar rules for English questions, and direct reference statements for general awareness items. Performance analytics after each attempt include accuracy, attempt rate, time spent per question, and an estimated all-India percentile so you know exactly where you stand against other candidates. This quiz is completely free to attempt. You only need a free AajExam account to track your performance across attempts, view detailed solutions and unlock the platform-wide analytics dashboard. The platform is mobile-friendly and works seamlessly on smartphones, tablets and desktops — so you can sharpen your series (Reasoning & Mental Aptitude) skills in any spare 15-minute window.

Number and Letter Series Quiz — Questions with Solutions

All 25 questions from this quiz with the correct answer and explanation. Attempt them yourself first, then open each solution to check your reasoning.

  1. Q1.Find the next number: 2, 5, 10, 17, ?

    • A.24
    • B.26
    • C.28
    • D.30
    Show answer

    Answer: B. 26

    Differences increase by 2 each time (3,5,7,9); 17+9=26.

  2. Q2.Find the next number: 1, 3, 6, 10, ?

    • A.13
    • B.14
    • C.15
    • D.16
    Show answer

    Answer: C. 15

    These are triangular numbers; differences increase by 1 each time; 10+5=15.

  3. Q3.Find the next letter: A, D, G, J, ?

    • A.K
    • B.L
    • C.M
    • D.N
    Show answer

    Answer: C. M

    This series skips 2 letters each time: A,D,G,J,M.

  4. Q4.Find the next number: 4, 8, 16, 32, ?

    • A.48
    • B.56
    • C.64
    • D.72
    Show answer

    Answer: C. 64

    Each term doubles the previous one; 32*2=64.

  5. Q5.Find the missing number: 100, 81, 64, 49, ?

    • A.36
    • B.30
    • C.25
    • D.40
    Show answer

    Answer: A. 36

    These are squares of decreasing numbers: 10^2,9^2,8^2,7^2,6^2=36.

  6. Q6.Find the next letter: Z, Y, X, W, ?

    • A.U
    • B.V
    • C.T
    • D.S
    Show answer

    Answer: B. V

    This series decreases alphabetically by 1 each time: Z,Y,X,W,V.

  7. Q7.Find the next number: 3, 9, 27, 81, ?

    • A.162
    • B.216
    • C.243
    • D.270
    Show answer

    Answer: C. 243

    Each term is multiplied by 3; 81*3=243.

  8. Q8.Find the missing number: 5, 11, 23, 47, ?

    • A.94
    • B.95
    • C.96
    • D.97
    Show answer

    Answer: B. 95

    Each term is doubled and 1 added: 47*2+1=95.

  9. Q9.Find the next letter: B, D, F, H, ?

    • A.I
    • B.J
    • C.K
    • D.L
    Show answer

    Answer: B. J

    This series skips one letter each time: B,D,F,H,J.

  10. Q10.Find the missing number: 2, 4, 8, 16, 32, ?

    • A.48
    • B.56
    • C.64
    • D.72
    Show answer

    Answer: C. 64

    Each term doubles the previous one; 32*2=64.

  11. Q11.Find the next number: 1, 4, 9, 16, 25, ?

    • A.30
    • B.32
    • C.36
    • D.40
    Show answer

    Answer: C. 36

    These are perfect squares: 1,4,9,16,25,36.

  12. Q12.Find the missing letter: C, F, I, L, ?

    • A.M
    • B.N
    • C.O
    • D.P
    Show answer

    Answer: C. O

    This series skips 2 letters each time: C,F,I,L,O.

  13. Q13.Find the next number: 6, 12, 24, 48, ?

    • A.72
    • B.84
    • C.96
    • D.108
    Show answer

    Answer: C. 96

    Each term doubles the previous one; 48*2=96.

  14. Q14.Find the missing number: 1, 2, 4, 7, 11, ?

    • A.14
    • B.15
    • C.16
    • D.17
    Show answer

    Answer: C. 16

    Differences increase by 1 each time (1,2,3,4,5); 11+5=16.

  15. Q15.Find the next letter: J, L, N, P, ?

    • A.Q
    • B.R
    • C.S
    • D.T
    Show answer

    Answer: B. R

    This series skips one letter each time: J,L,N,P,R.

  16. Q16.Find the next number: 10, 20, 40, 80, ?

    • A.120
    • B.140
    • C.160
    • D.180
    Show answer

    Answer: C. 160

    Each term doubles the previous one; 80*2=160.

  17. Q17.Find the missing number: 2, 3, 5, 8, 13, ?

    • A.18
    • B.19
    • C.20
    • D.21
    Show answer

    Answer: D. 21

    This is the Fibonacci-like series; each term is the sum of the two before it: 8+13=21.

  18. Q18.Find the next letter: M, K, I, G, ?

    • A.F
    • B.E
    • C.D
    • D.C
    Show answer

    Answer: B. E

    This series decreases by 2 letters each time: M,K,I,G,E.

  19. Q19.Find the next number: 7, 14, 28, 56, ?

    • A.98
    • B.100
    • C.112
    • D.120
    Show answer

    Answer: C. 112

    Each term doubles the previous one; 56*2=112.

  20. Q20.Find the missing number: 3, 7, 15, 31, ?

    • A.47
    • B.55
    • C.63
    • D.71
    Show answer

    Answer: C. 63

    Each term is doubled and 1 added: 31*2+1=63.

  21. Q21.Find the next letter: A, E, I, ?

    • A.M
    • B.O
    • C.U
    • D.N
    Show answer

    Answer: B. O

    This series lists English vowels in order: A,E,I,O.

  22. Q22.Find the next number: 5, 10, 20, 40, 80, ?

    • A.120
    • B.140
    • C.160
    • D.180
    Show answer

    Answer: C. 160

    Each term doubles the previous one; 80*2=160.

  23. Q23.Find the missing number: 1, 8, 27, 64, ?

    • A.100
    • B.121
    • C.125
    • D.144
    Show answer

    Answer: C. 125

    These are perfect cubes: 1,8,27,64,125.

  24. Q24.Find the next letter: D, G, J, M, ?

    • A.N
    • B.O
    • C.P
    • D.Q
    Show answer

    Answer: C. P

    This series skips 2 letters each time: D,G,J,M,P.

  25. Q25.Find the missing number: 4, 6, 9, 13, 18, ?

    • A.22
    • B.23
    • C.24
    • D.25
    Show answer

    Answer: C. 24

    Differences increase by 1 each time (2,3,4,5,6); 18+6=24.

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Frequently Asked Questions

Is Number and Letter Series Quiz free to attempt on AajExam?

Yes. Number and Letter Series Quiz is completely free. You only need a free AajExam account to track your score, view detailed solutions and unlock cross-attempt analytics.

How long does it take to complete Number and Letter Series Quiz?

Number and Letter Series Quiz runs on a 25-minute timer in real exam-style conditions. The clock starts the moment you click Start, mirroring the time pressure of the actual exam.

Are detailed solutions provided?

Yes. Every question on Number and Letter Series Quiz ships with a complete step-by-step solution, the underlying concept, and (where applicable) shortcut tricks. You can also discuss any question with the AajExam community.

Can I attempt Number and Letter Series Quiz multiple times?

Yes. You can attempt this quiz as many times as you like. Each attempt is recorded separately so you can track improvement in score, accuracy and time-management.

Which government exams does this quiz prepare me for?

series questions appear regularly in SSC CGL, CHSL, MTS, GD; IBPS PO, Clerk; SBI PO, Clerk; RRB NTPC, Group D; UPSC prelims and most State PSC exams. The specific weightage varies by exam — check the exam pattern on the corresponding AajExam exam page for details.