Number System MCQ
1. Which of the following is a rational number ?
A) √2 B) √5 C) 1/3 D) π
Ans: 1/3
Explanation: A rational number can be expressed as a fraction of two integers. 1/3 is a fraction, so it is rational. √2, √5, and π are irrational.
2. The binary equivalent of 8 is:
A) 100 B) 1010 C) 1000 D) 111
Ans: 1000
Explanation: 8 in decimal = 1000 in binary (2³ = 8).
3. Which of the following is a prime number ?
A) 21 B) 37 C) 51 D) 69
Ans: 37
Explanation: A prime number has only two factors: 1 and itself. 37 is prime.
4. The largest 4-digit number is:
A) 999 B) 1000 C) 9999 D) 10000
Ans: 9999
Explanation: 4-digit numbers range from 1000 to 9999.
5. The HCF of 24 and 36 is:
A) 2 B) 6 C) 8 D) 12
Ans: 12
Explanation: Factors of 24: 1,2,3,4,6,8,12,24; Factors of 36: 1,2,3,4,6,9,12,18,36
Highest common factor = 12
6. Which base is used in the hexadecimal system ?
A) 2 B) 8 C) 10 D) 16
Ans: 16
Explanation: Hexadecimal system uses base 16 (0–9 and A–F).
7. The Roman numeral for 100 is:
A) L B) C C) D D) M
Ans: C
Explanation: In Roman numerals: L = 50, C = 100, D = 500, M = 1000
8. A number divisible by 5 must end in:
A) 0 or 2 B) 1 or 9 C) 5 or 0 D) 7 or 3
Ans: 5 or 0
Explanation: Numbers divisible by 5 always end in 0 or 5.
9. The decimal equivalent of binary 111 is:
A) 5 B) 6 C) 7 D) 8
Ans: 7
Explanation: 111 in binary = 1×2² + 1×2¹ + 1×2⁰ = 4 + 2 + 1 = 7
10. π (pi) is:
A) Rational B) Whole C) Irrational D) Natural
Ans: Irrational
Explanation: π cannot be expressed as a fraction of two integers; it is non-terminating and non-repeating.
11. Which of the following number is greater than −17 ?
(a) −2 (b) −10 (c) 0 (d) −3
Ans: (c) 0
Explanation: On the number line, 0 lies to the right of −17, so it is greater.
12. The preceding number of 1 on the number line is:
(a) 0 (b) 1 (c) 2 (d) −2
Ans: (a) 0
Explanation: The number just before 1 is 0.
13. Which number is 5 more than −37 ?
(a) −32 (b) 2 (c) 8 (d) −8
Ans: (a) −32
Explanation: −37 + 5 = −32.
14. 7 steps to the left of 4 on the number line gives:
(a) 3 (b) 11 (c) −11 (d) −3
Ans: (d) −3
Explanation: Moving left means subtraction: 4 − 7 = −3.
15. 2 steps to the right of −1 on the number line gives:
(a) 0 (b) 1 (c) −3 (d) 3
Ans: (b) 1
Explanation: Moving right means addition: −1 + 2 = 1.
16. The integer succeeding −9 is:
(a) −10 (b) 10 (c) −8 (d) 8
Ans: (c) −8
Explanation: The next number after −9 is −8.
17. What will be the opposite of 3 km south ?
(a) 3 km east (b) 3 km north (c) 3 km north-east (d) 3 km west
Ans: (b) 3 km north
Explanation: Opposite direction of south is north.
18. Which of the following set of numbers is in descending order ?
(a) 2, −2, 1, −1
(b) 0, 1, 2, 3
(c) 1, 0, −1, −2
(d) −3, −2, −1, 0
Ans: (c) 1, 0, −1, −2
Explanation: Descending order means greatest to smallest.
19. Which of the following statements is false ?
(a) 0 lies to the left of −1
(b) 2 lies to the right of 1
(c) 1 lies to the right of 0
(d) −2 lies to the left of −1
Ans: 0 lies to the left of −1
Explanation: 0 lies to the right, not left, of −1.
12. 5 added to 1 gives:
(a) 4 (b) −4 (c) 6 (d) −6
Ans: (c) 6
Explanation: 1 + 5 = 6.