Quantitative AptitudeNumber Systemmixed

Number Theory Quiz

Practice quiz on Number Theory (Numerical Ability (Quantitative Aptitude)). 10 exam-style questions with explanations.

10
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10
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About This Quiz

Practice quiz on Number Theory (Numerical Ability (Quantitative Aptitude)). 10 exam-style questions with explanations. Number Theory Quiz is a free, 10-minute, 10-mark practice quiz on AajExam rated at mixed difficulty, designed to help candidates preparing for SSC, UPSC, Banking, Railway and State PSC government competitive exams sharpen their command of Number System (Quantitative 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 Theory 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 10-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. After mastering this quiz, explore the 6 related quizzes linked below to broaden your topic coverage. 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 Number System (Quantitative Aptitude) skills in any spare 15-minute window.
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Number Theory Quiz — Questions with Solutions

All 10 questions from this quiz with the correct answer and explanation. Attempt them yourself first, then open each solution to check your reasoning.

  1. Q1.The HCF of 18 and 24 is

    • A.2
    • B.6
    • C.3
    • D.12
    Show answer

    Answer: B. 6

    Common factors give 6.

  2. Q2.The LCM of 4, 6 and 8 is

    • A.24
    • B.12
    • C.32
    • D.48
    Show answer

    Answer: A. 24

    LCM = 24.

  3. Q3.Which is a prime number?

    • A.91
    • B.87
    • C.97
    • D.93
    Show answer

    Answer: C. 97

    97 is prime.

  4. Q4.The number of divisors of 12 is

    • A.5
    • B.4
    • C.6
    • D.8
    Show answer

    Answer: C. 6

    1,2,3,4,6,12.

  5. Q5.The sum of the first 10 natural numbers is

    • A.65
    • B.50
    • C.55
    • D.45
    Show answer

    Answer: C. 55

    n(n+1)/2 = 55.

  6. Q6.The remainder when 2^10 is divided by 3 is

    • A.3
    • B.1
    • C.0
    • D.2
    Show answer

    Answer: B. 1

    2^10 = 1024 = 3 x 341 + 1.

  7. Q7.Co-prime numbers have HCF equal to

    • A.the smaller number
    • B.2
    • C.0
    • D.1
    Show answer

    Answer: D. 1

    HCF of co-primes is 1.

  8. Q8.The product of HCF and LCM of two numbers equals

    • A.The sum of the numbers
    • B.Their difference
    • C.The product of the numbers
    • D.Their ratio
    Show answer

    Answer: C. The product of the numbers

    HCF x LCM = a x b.

  9. Q9.The smallest 3-digit number divisible by 7 is

    • A.98
    • B.100
    • C.105
    • D.112
    Show answer

    Answer: C. 105

    7 x 15 = 105.

  10. Q10.Which of the following is a perfect number?

    • A.24
    • B.28
    • C.32
    • D.30
    Show answer

    Answer: B. 28

    1+2+4+7+14 = 28.

Frequently Asked Questions

Is Number Theory Quiz free to attempt on AajExam?

Yes. Number Theory 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 Theory Quiz?

Number Theory Quiz runs on a 10-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 Theory 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 Theory 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?

Number System 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.

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