Number System MCQs
1. Which is the smallest prime number?
A) 0
B) 1
C) 2
D) 3
Answer: C) 2
2. Which of the following is not a prime number?
A) 11
B) 13
C) 15
D) 17
Answer: C) 15
3. The HCF of 12 and 18 is:
A) 3
B) 6
C) 9
D) 12
Answer: B) 6
4. The LCM of 8 and 12 is:
A) 24
B) 48
C) 36
D) 96
Answer: A) 24
5. How many factors does 24 have?
A) 6
B) 7
C) 8
D) 9
Answer: C) 8
6. Which number is divisible by 3?
A) 124
B) 235
C) 321
D) 401
Answer: C) 321
7. The remainder when 25 is divided by 4 is:
A) 0
B) 1
C) 2
D) 3
Answer: B) 1
8. Which is a perfect square?
A) 121
B) 122
C) 123
D) 124
Answer: A) 121
9. Square root of 144 is:
A) 11
B) 12
C) 13
D) 14
Answer: B) 12
10. Cube root of 216 is:
A) 4
B) 5
C) 6
D) 7
Answer: C) 6
11. Which number is divisible by 11?
A) 242
B) 243
C) 244
D) 245
Answer: A) 242
12. The product of HCF and LCM of two numbers equals:
A) Sum of numbers
B) Difference of numbers
C) Product of numbers
D) Square of numbers
Answer: C) Product of numbers
13. Which of the following is an even number?
A) 125
B) 237
C) 468
D) 999
Answer: C) 468
14. Binary equivalent of decimal 10 is:
A) 1010
B) 1001
C) 1100
D) 1110
Answer: A) 1010
15. Decimal equivalent of binary 101 is:
A) 4
B) 5
C) 6
D) 7
Answer: B) 5
16. Which is a composite number?
A) 7
B) 11
C) 13
D) 21
Answer: D) 21
17. Number of prime factors of 30:
A) 2
B) 3
C) 4
D) 5
Answer: B) 3
18. The successor of 999 is:
A) 998
B) 999
C) 1000
D) 1001
Answer: C) 1000
19. The predecessor of 1000 is:
A) 998
B) 999
C) 1000
D) 1001
Answer: B) 999
20. Which number is divisible by 9?
A) 324
B) 325
C) 326
D) 327
Answer: A) 324
21. HCF of 15 and 25:
A) 3
B) 5
C) 10
D) 15
Answer: B) 5
22. LCM of 5 and 7:
A) 12
B) 30
C) 35
D) 40
Answer: C) 35
23. A number divisible by both 2 and 5 must end with:
A) 0
B) 2
C) 5
D) 8
Answer: A) 0
24. Which is an irrational number?
A) 1/2
B) 0.75
C) √2
D) 5
Answer: C) √2
25. Which is a rational number?
A) π
B) √3
C) √5
D) 3/7
Answer: D) 3/7
26. The sum of first 10 natural numbers:
A) 45
B) 50
C) 55
D) 60
Answer: C) 55
27. The smallest natural number is:
A) 0
B) 1
C) 2
D) -1
Answer: B) 1
28. The smallest whole number is:
A) 0
B) 1
C) -1
D) 2
Answer: A) 0
29. Which number is neither prime nor composite?
A) 0
B) 1
C) 2
D) 3
Answer: B) 1
30. The units digit of 7²³ is:
A) 1
B) 3
C) 7
D) 9
Answer: B) 3
31. 2⁵ equals:
A) 16
B) 24
C) 32
D) 64
Answer: C) 32
32. 3³ equals:
A) 9
B) 18
C) 27
D) 81
Answer: C) 27
33. Which is a perfect cube?
A) 125
B) 126
C) 127
D) 128
Answer: A) 125
34. Greatest 3-digit number:
A) 999
B) 1000
C) 998
D) 990
Answer: A) 999
35. Smallest 4-digit number:
A) 999
B) 1000
C) 1001
D) 1111
Answer: B) 1000
36. Number of zeros in 1000:
A) 2
B) 3
C) 4
D) 5
Answer: B) 3
37. Which is divisible by 4?
A) 214
B) 216
C) 218
D) 222
Answer: B) 216
38. Remainder when 99 is divided by 10:
A) 0
B) 1
C) 9
D) 10
Answer: C) 9
39. Prime factorization of 36:
A) 2² × 3²
B) 2 × 3²
C) 2² × 3
D) 6²
Answer: A) 2² × 3²
40. HCF of 24, 36 and 60:
A) 6
B) 12
C) 18
D) 24
Answer: B) 12
41. LCM of 4, 6 and 8:
A) 12
B) 18
C) 24
D) 48
Answer: C) 24
42. Number of divisors of 36:
A) 7
B) 8
C) 9
D) 10
Answer: C) 9
43. Which is an odd prime number?
A) 2
B) 4
C) 9
D) 11
Answer: D) 11
44. The sum of digits of 987:
A) 22
B) 23
C) 24
D) 25
Answer: C) 24
45. A number ending in 5 is always divisible by:
A) 2
B) 3
C) 5
D) 10
Answer: C) 5
46. Which number is divisible by both 3 and 9?
A) 72
B) 74
C) 76
D) 78
Answer: A) 72
47. The remainder when 100 is divided by 7:
A) 1
B) 2
C) 3
D) 4
Answer: B) 2
48. Which is a twin prime pair?
A) 11, 13
B) 12, 14
C) 15, 17
D) 21, 23
Answer: A) 11, 13
49. The greatest common factor of 48 and 72:
A) 12
B) 24
C) 36
D) 48
Answer: B) 24
50. Which number is not divisible by 2?
A) 102
B) 204
C) 305
D) 408
Answer: C) 305