Number System MCQ Quiz – Set 1

🧮 Number System MCQ Quiz – Set 1

This quiz consists of 10 multiple-choice questions based on the topic Number System. It’s designed for competitive exams like SSC, Railways, UPSC, and Class X/XI Math practice. Each question includes the correct answer and a brief explanation.

1. Which of the following is a rational number?

A) √2
B) π
C) 4/5
D) e

✅ Answer: C) 4/5

Explanation: Rational numbers can be written in the form p/q. 4/5 is rational.

2. The smallest prime number is:

A) 1
B) 2
C) 3
D) 0

✅ Answer: B) 2

Explanation: 2 is the smallest and only even prime number.

3. Which of the following is a composite number?

A) 3
B) 7
C) 9
D) 11

✅ Answer: C) 9

Explanation: Composite numbers have more than two factors. 9 = 3 × 3.

4. Which of the following is an irrational number?

A) 0.5
B) √3
C) 3/4
D) -2

✅ Answer: B) √3

Explanation: √3 is non-terminating and non-repeating, hence irrational.

5. How many prime numbers are there between 1 and 10?

A) 2
B) 3
C) 4
D) 5

✅ Answer: D) 5

Explanation: Primes up to 10 are 2, 3, 5, 7, and 11. That’s 5.

6. What is the LCM of 4 and 6?

A) 24
B) 6
C) 12
D) 8

✅ Answer: C) 12

Explanation: 12 is the least number divisible by both 4 and 6.

7. The HCF of 18 and 24 is:

A) 6
B) 12
C) 3
D) 18

✅ Answer: A) 6

Explanation: 6 is the highest number dividing both 18 and 24.

8. Which of the following is not a whole number?

A) 0
B) 5
C) 8.3
D) 10

✅ Answer: C) 8.3

Explanation: Whole numbers are non-negative integers. 8.3 is a decimal.

9. A number which has only two factors is called:

A) Even
B) Odd
C) Prime
D) Composite

✅ Answer: C) Prime

Explanation: Prime numbers have exactly two factors: 1 and itself.

10. Which of these numbers is divisible by 11?

A) 1331
B) 121
C) 1001
D) All of the above

✅ Answer: D) All of the above

Explanation: All are multiples of 11.

🧮 Number System MCQ Quiz – Set 2

This is the second set of multiple-choice questions (Q11–Q20) from the Number System topic, including answers and brief explanations for better understanding.

11. Which of the following is not a prime number?

A) 2
B) 11
C) 15
D) 17

✅ Answer: C) 15

Explanation: 15 has more than two factors (1, 3, 5, 15), so it’s not a prime.

12. Which number is both a square and a cube?

A) 16
B) 64
C) 81
D) 100

✅ Answer: B) 64

Explanation: 64 = 8² and also 4³. So it’s both a square and a cube.

13. What is the place value of 7 in the number 5,743?

A) 7
B) 70
C) 700
D) 7000

✅ Answer: C) 700

Explanation: In 5,743, the 7 is in the hundreds place. 7 × 100 = 700.

14. Which of the following is the smallest rational number?

A) -3
B) 0
C) 1
D) -1/2

✅ Answer: A) -3

Explanation: Among the options, -3 is the smallest rational number.

15. A number is divisible by 3 if:

A) It ends in 3
B) It’s even
C) The sum of its digits is divisible by 3
D) None of the above

✅ Answer: C) The sum of its digits is divisible by 3

Explanation: This is a standard divisibility rule for 3.

16. What is the greatest 2-digit prime number?

A) 89
B) 97
C) 93
D) 99

✅ Answer: B) 97

Explanation: 97 is the largest prime number less than 100.

17. Which of these is not an integer?

A) -5
B) 0
C) 1.2
D) 8

✅ Answer: C) 1.2

Explanation: Integers do not include decimals or fractions.

18. The product of any number and zero is:

A) That number
B) One
C) Zero
D) Undefined

✅ Answer: C) Zero

Explanation: Any number × 0 = 0.

19. The number 1 is:

A) Prime
B) Composite
C) Neither prime nor composite
D) Both

✅ Answer: C) Neither prime nor composite

Explanation: 1 is a unique number with only one factor, hence it’s neither.

20. Which number is a factor of every number?

A) 0
B) 1
C) 2
D) 10

✅ Answer: B) 1

Explanation: 1 is a universal factor — it divides every number.

🧮 Number System MCQ Quiz – Set 3

This is the third set of multiple-choice questions (Q21–Q30) on the Number System, ideal for school exams and competitive tests.

21. What is the sum of the first five natural numbers?

A) 10
B) 15
C) 20
D) 25

✅ Answer: B) 15

Explanation: 1 + 2 + 3 + 4 + 5 = 15

22. Which is the smallest 3-digit number?

A) 100
B) 101
C) 111
D) 99

✅ Answer: A) 100

Explanation: 100 is the smallest 3-digit number.

23. Which of the following is not divisible by 5?

A) 20
B) 35
C) 42
D) 50

✅ Answer: C) 42

Explanation: A number divisible by 5 must end in 0 or 5.

24. The difference between the greatest and smallest 2-digit number is:

A) 80
B) 89
C) 90
D) 99

✅ Answer: B) 89

Explanation: Greatest = 99, Smallest = 10, Difference = 89

25. Which of the following is a perfect square?

A) 20
B) 36
C) 45
D) 50

✅ Answer: B) 36

Explanation: 36 = 6²

26. What is the predecessor of 1?

A) 0
B) 2
C) -1
D) 10

✅ Answer: C) -1

Explanation: Predecessor means the number before. Before 1 is -1.

27. Which is a co-prime pair?

A) 4 and 6
B) 3 and 5
C) 10 and 20
D) 12 and 18

✅ Answer: B) 3 and 5

Explanation: Co-primes have HCF = 1. 3 and 5 share no common factor other than 1.

28. Which digit will come next in the pattern: 2, 4, 8, 16, ___?

A) 18
B) 24
C) 30
D) 32

✅ Answer: D) 32

Explanation: Each term is multiplied by 2. So next = 16 × 2 = 32

29. Which of the following is a multiple of both 3 and 4?

A) 9
B) 12
C) 16
D) 18

✅ Answer: B) 12

Explanation: 12 is divisible by both 3 and 4.

30. If a number is divisible by 6, it must also be divisible by:

A) 2 and 3
B) 3 and 5
C) 2 and 5
D) 3 and 4

✅ Answer: A) 2 and 3

Explanation: 6 = 2 × 3, so any number divisible by 6 is divisible by both 2 and 3.

🧮 Number System MCQ Quiz – Set 4

This is the fourth set of multiple-choice questions (Q31–Q40) on the Number System. All questions include correct answers and explanations for enhanced learning.

31. What is the even prime number?

A) 1
B) 2
C) 3
D) 4

✅ Answer: B) 2

Explanation: 2 is the only even prime number.

32. Which number is divisible by both 2 and 9?

A) 18
B) 36
C) 27
D) 22

✅ Answer: B) 36

Explanation: 36 is divisible by both 2 and 9.

33. Which of the following is a negative integer?

A) 0
B) -3
C) 2.5
D) 4

✅ Answer: B) -3

Explanation: -3 is a whole number less than 0, thus a negative integer.

34. Which of the following is not a natural number?

A) 0
B) 1
C) 2
D) 3

✅ Answer: A) 0

Explanation: Natural numbers start from 1. Zero is a whole number, not a natural number.

35. The smallest 4-digit number is:

A) 1000
B) 100
C) 999
D) 1001

✅ Answer: A) 1000

Explanation: 1000 is the first number with four digits.

36. What is the HCF of 9 and 28?

A) 1
B) 3
C) 7
D) 9

✅ Answer: A) 1

Explanation: 9 and 28 have no common factor other than 1. So they are co-prime.

37. Which of the following is a multiple of 7?

A) 14
B) 15
C) 16
D) 18

✅ Answer: A) 14

Explanation: 14 = 7 × 2

38. How many whole numbers are there between 12 and 20?

A) 8
B) 9
C) 7
D) 6

✅ Answer: C) 7

Explanation: Whole numbers between 12 and 20 are 13 to 19 → 7 numbers.

39. The square of 11 is:

A) 111
B) 121
C) 101
D) 131

✅ Answer: B) 121

Explanation: 11 × 11 = 121

40. Which of these is not a factor of 60?

A) 3
B) 4
C) 6
D) 11

✅ Answer: D) 11

Explanation: 11 does not divide 60 exactly, so it is not a factor.

🧮 Number System MCQ Quiz – Set 5

This is the fifth set of multiple-choice questions (Q41–Q50) on the Number System. Each question comes with a correct answer and explanation to help build strong foundational understanding.

41. Which of these is a prime number?

A) 49
B) 39
C) 37
D) 33

✅ Answer: C) 37

Explanation: 37 has only two factors — 1 and 37, making it a prime number.

42. Which of the following numbers is a perfect cube?

A) 8
B) 12
C) 20
D) 24

✅ Answer: A) 8

Explanation: 8 = 2³ is a perfect cube.

43. What is the sum of the digits of the number 234?

A) 8
B) 9
C) 10
D) 12

✅ Answer: D) 12

Explanation: 2 + 3 + 4 = 9

44. Which number is both a factor and a multiple of 6?

A) 3
B) 6
C) 12
D) 18

✅ Answer: B) 6

Explanation: 6 is both a factor of itself and a multiple.

45. The sum of two even numbers is always:

A) Odd
B) Prime
C) Even
D) Composite

✅ Answer: C) Even

Explanation: Even + Even = Even. Example: 4 + 6 = 10

46. What is the place value of 4 in 7423?

A) 4
B) 40
C) 400
D) 4000

✅ Answer: C) 400

Explanation: The digit 4 is in the hundreds place → 4 × 100 = 400

47. What is the smallest prime number greater than 50?

A) 51
B) 53
C) 55
D) 57

✅ Answer: B) 53

Explanation: 53 is the next prime number after 50.

48. The product of two odd numbers is:

A) Always even
B) Always odd
C) Sometimes odd
D) Cannot be determined

✅ Answer: B) Always odd

Explanation: Odd × Odd = Odd. Example: 3 × 5 = 15

49. The number 0 is:

A) Natural number
B) Whole number
C) Prime number
D) Composite number

✅ Answer: B) Whole number

Explanation: 0 is a whole number but not a natural number.

50. Which of the following is the greatest 2-digit number?

A) 90
B) 98
C) 99
D) 100

✅ Answer: C) 99

Explanation: 99 is the largest number with 2 digits.