1. Which of the following is a rational number?
A) √2
B) π
C) 3/7
D) e
Answer: C) 3/7
Explanation: A rational number is a number that can be expressed as a fraction of two integers. 3/7 is rational. √2, π, and e are irrational.
2. Which of the following numbers is not a whole number?
A) 0
B) 1
C) 2
D) -1
Answer: D) -1
Explanation: Whole numbers start from 0 and include all positive integers. Negative numbers are not whole numbers.
3. What is the smallest prime number?
A) 0
B) 1
C) 2
D) 3
Answer: C) 2
Explanation: 2 is the smallest and the only even prime number.
4. What is the HCF of 18 and 24?
A) 2
B) 3
C) 6
D) 12
Answer: C) 6
Explanation: The highest common factor (HCF) of 18 and 24 is 6.
5. Every integer is a:
A) Rational number
B) Natural number
C) Whole number
D) Prime number
Answer: A) Rational number
Explanation: Every integer can be written as a fraction (e.g., -2 = -2/1), so it is a rational number.
6. The decimal representation of 1/3 is:
A) 0.33
B) 0.333
C) 0.333… (repeating)
D) 0.34
Answer: C) 0.333… (repeating)
Explanation: 1 divided by 3 gives a repeating decimal: 0.333…
7. Which number is not a factor of 36?
A) 2
B) 3
C) 5
D) 6
Answer: C) 5
Explanation: 5 is not a factor of 36, as 36 ÷ 5 is not an integer.
8. The LCM of 12 and 18 is:
A) 36
B) 48
C) 24
D) 72
Answer: A) 36
Explanation: LCM of 12 and 18 is 36, the smallest number divisible by both.
9. Which of the following is an irrational number?
A) 1/4
B) 0.25
C) √5
D) 7
Answer: C) √5
Explanation: √5 cannot be expressed as a fraction, hence irrational.
10. The number 121 is a:
A) Prime number
B) Composite number
C) Irrational number
D) Whole number
Answer: B) Composite number
Explanation: 121 = 11 × 11, so it is a composite number.
11. The number of prime numbers between 1 and 20 is:
A) 6
B) 7
C) 8
D) 9
Answer: C) 8
Explanation: The primes are: 2, 3, 5, 7, 11, 13, 17, 19.
12. What is the value of 2⁵?
A) 10
B) 25
C) 32
D) 64
Answer: C) 32
Explanation: 2⁵ = 2×2×2×2×2 = 32
13. Which of these numbers is divisible by 9?
A) 123
B) 135
C) 154
D) 172
Answer: B) 135
Explanation: 1+3+5 = 9, and 9 is divisible by 9.
14. Which is the smallest odd prime number?
A) 1
B) 2
C) 3
D) 5
Answer: C) 3
Explanation: The smallest odd prime is 3. 2 is even.
15. What is 1001 × 101?
A) 101101
B) 102201
C) 100101
D) 101101
Answer: D) 101101
Explanation: Direct multiplication gives 101101.
16. A number divisible by both 2 and 3 is divisible by:
A) 5
B) 6
C) 4
D) 8
Answer: B) 6
Explanation: LCM of 2 and 3 is 6.
17. Which number is both a square and a cube?
A) 8
B) 16
C) 64
D) 81
Answer: C) 64
Explanation: 64 = 8² = 4³
18. 0 is a:
A) Natural number
B) Whole number
C) Prime number
D) Irrational number
Answer: B) Whole number
Explanation: 0 is a whole number, but not natural or prime.
19. What is the unit digit of 7⁴?
A) 1
B) 3
C) 9
D) 1
Answer: A) 1
Explanation: 7⁴ = 2401 → unit digit = 1
20. Which number is divisible by 11?
A) 121
B) 143
C) 231
D) 351
Answer: A) 121
Explanation: 121 ÷ 11 = 11, so it is divisible.
21. How many digits are there in 10⁵?
A) 4
B) 5
C) 6
D) 7
Answer: C) 6
Explanation: 10⁵ = 100000 → 6 digits
22. A number which is divisible by 2, 3, and 4 must be divisible by:
A) 6
B) 8
C) 12
D) 24
Answer: C) 12
Explanation: LCM(2,3,4) = 12
23. Which is a twin prime pair?
A) 3 and 5
B) 7 and 11
C) 11 and 13
D) 17 and 19
Answer: C) 11 and 13
Explanation: Twin primes differ by 2. So 11 and 13 are a pair.
24. 999 is divisible by:
A) 3
B) 9
C) 27
D) All of the above
Answer: D) All of the above
Explanation: 999 ÷ 3 = 333; ÷9 = 111; ÷27 = 37
25. The sum of first 10 natural numbers is:
A) 45
B) 50
C) 55
D) 60
Answer: C) 55
Explanation: Sum = n(n+1)/2 = 10(11)/2 = 55
26. The product of two odd numbers is:
A) Even
B) Odd
C) Prime
D) Composite
Answer: B) Odd
Explanation: Odd × Odd = Odd
27. Which of the following is not a perfect square?
A) 121
B) 144
C) 169
D) 130
Answer: D) 130
Explanation: 130 is not a square of any integer.
28. The number 81 is equal to:
A) 9²
B) 3³
C) 8²
D) 7²
Answer: A) 9²
Explanation: 9×9 = 81
29. 100 is divisible by which of the following?
A) 6
B) 9
C) 10
D) 11
Answer: C) 10
Explanation: 100 ÷ 10 = 10
30. Which of the following is a composite number?
A) 3
B) 5
C) 9
D) 7
Answer: C) 9
Explanation: 9 = 3 × 3, so it’s not prime.
31. The only even prime number is:
A) 0
B) 2
C) 4
D) 6
Answer: B) 2
Explanation: 2 is the only even number divisible only by 1 and itself.
32. Prime factorization of 30 is:
A) 2 × 3 × 5
B) 2 × 5 × 6
C) 3 × 10
D) 2 × 15
Answer: A) 2 × 3 × 5
Explanation: Prime factors of 30 are 2, 3, and 5.
33. Which number is divisible by both 3 and 5?
A) 10
B) 12
C) 15
D) 20
Answer: C) 15
Explanation: 15 ÷ 3 = 5, and 15 ÷ 5 = 3
34. The square of 11 is:
A) 111
B) 121
C) 131
D) 141
Answer: B) 121
Explanation: 11 × 11 = 121
35. Which number has both 2 and 3 as its factors?
A) 5
B) 6
C) 7
D) 9
Answer: B) 6
Explanation: 6 = 2 × 3
36. The number 0 is:
A) Natural number
B) Whole number
C) Prime number
D) Negative number
Answer: B) Whole number
Explanation: 0 is the first whole number but not a natural number.
37. What is the sum of the first 5 odd numbers?
A) 15
B) 20
C) 25
D) 30
Answer: C) 25
Explanation: 1+3+5+7+9 = 25
38. Which of these is a factor of 45?
A) 4
B) 5
C) 7
D) 8
Answer: B) 5
Explanation: 45 ÷ 5 = 9
39. How many prime numbers are there between 10 and 20?
A) 2
B) 3
C) 4
D) 5
Answer: C) 4
Explanation: 11, 13, 17, 19
40. Which number is a cube number?
A) 8
B) 10
C) 12
D) 15
Answer: A) 8
Explanation: 2³ = 8
41. The sum of even numbers from 1 to 10 is:
A) 25
B) 30
C) 35
D) 40
Answer: B) 30
Explanation: 2+4+6+8+10 = 30
42. Which number is a multiple of 4 but not of 8?
A) 8
B) 12
C) 16
D) 24
Answer: B) 12
Explanation: 12 is divisible by 4, but not by 8.
43. The next prime number after 19 is:
A) 21
B) 23
C) 25
D) 27
Answer: B) 23
Explanation: Next prime after 19 is 23
44. What is the LCM of 4 and 6?
A) 8
B) 10
C) 12
D) 16
Answer: C) 12
Explanation: 4 and 6 LCM = 12
45. 10³ = ?
A) 100
B) 1000
C) 10000
D) 10
Answer: B) 1000
Explanation: 10³ = 10 × 10 × 10 = 1000
46. What is the HCF of 20 and 28?
A) 2
B) 4
C) 6
D) 8
Answer: B) 4
Explanation: HCF(20, 28) = 4
47. The smallest 3-digit number is:
A) 001
B) 010
C) 100
D) 101
Answer: C) 100
Explanation: Smallest 3-digit number = 100
48. Which is an even prime number?
A) 1
B) 2
C) 4
D) 6
Answer: B) 2
Explanation: Only even prime is 2
49. 5² = ?
A) 10
B) 20
C) 25
D) 30
Answer: C) 25
Explanation: 5² = 5 × 5 = 25
50. Which number is divisible by 2, 3, and 6?
A) 10
B) 12
C) 15
D) 18