Number Theory Quiz
Practice quiz on Number Theory (Numerical Ability (Quantitative Aptitude)). 10 exam-style questions with explanations.
About This Quiz
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.
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.
Q2.The LCM of 4, 6 and 8 is
- A.24
- B.12
- C.32
- D.48
Show answer
Answer: A. 24
LCM = 24.
Q3.Which is a prime number?
- A.91
- B.87
- C.97
- D.93
Show answer
Answer: C. 97
97 is prime.
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.
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.
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.
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.
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.
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.
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.