1. (57)₈ in binary is:
- 111101
- 110111
- 101011
- 101111
Answer: D) 101111
Explanation: 5 = 101, 7 = 111.
MCQs / Computer Science / Number Systems and Conversions
Number Systems and Conversions MCQs — Computer Science
55 multiple-choice questions on Number Systems and Conversions from Computer Science, each with the correct answer and, where available, a teacher's explanation. Read through them to revise the chapter, then practise the same questions one by one to test yourself.
2. (10)₁₀ in binary is:
- 1010
- 1100
- 0110
- 1001
Answer: A) 1010
Explanation: 8 + 2 = 10.
3. (11010110)₂ in octal is:
- 326
- 362
- 623
- 316
Answer: A) 326
Explanation: 011 010 110 → 3 2 6.
4. In binary, 1 + 1 equals:
- 0
- 11
- 2
- 10
Answer: D) 10
Explanation: Write 0, carry 1.
5. (1000000)₂ in decimal is:
- 32
- 128
- 100
- 64
Answer: D) 64
Explanation: 1×2⁶ = 64.
6. (45)₁₀ in binary is:
- 101011
- 110101
- 100101
- 101101
Answer: D) 101101
Explanation: 32 + 8 + 4 + 1 = 45.
7. The leftmost bit of a binary number is called the:
- parity bit
- Least Significant Bit (LSB)
- Most Significant Bit (MSB)
- stop bit
Answer: C) Most Significant Bit (MSB)
Explanation: It has the highest place value.
8. (17)₈ in hexadecimal is:
- F
- 11
- E
- 17
Answer: A) F
Explanation: (17)₈ = 15 = F.
9. (1101)₂ − (0110)₂ equals:
- 0011
- 0101
- 0111
- 1011
Answer: C) 0111
Explanation: 13 − 6 = 7.
10. (20)₁₆ in octal is:
- 20
- 40
- 32
- 16
Answer: B) 40
Explanation: 0010 0000 → 100 000 → 40.
11. (26)₁₀ in hexadecimal is:
- 2A
- 1B
- 1A
- 26
Answer: C) 1A
Explanation: 16 + 10 = 26.
12. (234)₈ in decimal is:
- 234
- 146
- 164
- 156
Answer: D) 156
Explanation: 128 + 24 + 4 = 156.
13. (110101)₂ in octal is:
- 35
- 53
- 65
- 56
Answer: C) 65
Explanation: 110 = 6, 101 = 5.
14. (37)₁₀ in binary is:
- 100110
- 100101
- 101001
- 110001
Answer: B) 100101
Explanation: 32 + 4 + 1 = 37.
15. Which digits are used in the octal number system?
- 0 to 9 and A to F
- 0 to 7
- 0 and 1
- 0 to 8
Answer: B) 0 to 7
Explanation: Octal has eight digits.
16. (156)₁₀ in octal is:
- 234
- 324
- 243
- 156
Answer: A) 234
Explanation: 2×64 + 3×8 + 4 = 156.
17. (10111100)₂ in hexadecimal is:
- BC
- 274
- B8
- CB
Answer: A) BC
Explanation: 1011 = B, 1100 = C.
18. (0.5)₁₀ in binary is:
- 0.5
- 0.11
- 0.1
- 0.01
Answer: C) 0.1
Explanation: 0.5 × 2 = 1.0 → 1.
19. The base of the binary number system is:
- 10
- 2
- 16
- 8
Answer: B) 2
Explanation: Binary uses only 0 and 1.
20. In hexadecimal, the digit F represents the decimal value:
- 16
- 10
- 15
- 14
Answer: C) 15
Explanation: A=10 … F=15.
21. (255)₁₀ in hexadecimal is:
- 100
- EF
- FF
- FE
Answer: C) FF
Explanation: 15×16 + 15 = 255.
22. (25)₁₀ in binary is:
- 11001
- 10011
- 10101
- 11010
Answer: A) 11001
Explanation: 16 + 8 + 1 = 25.
23. (9C)₁₆ in binary is:
- 10010110
- 10011100
- 10101100
- 11001001
Answer: B) 10011100
Explanation: 9 = 1001, C = 1100.
24. (0.101)₂ in decimal is:
- 0.75
- 0.5
- 0.625
- 0.101
Answer: C) 0.625
Explanation: 0.5 + 0.125.
25. Which of the following is NOT a valid octal number?
- 128
- 777
- 105
- 127
Answer: A) 128
Explanation: 8 is not an octal digit.
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