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SECTION 1: NUMBER SYSTEMS & CONVERSIONS (Questions 1–30)
1. What is the decimal equivalent of the binary number 1011₂?
A) 9
B) 11
C) 13
D) 15
Answer: B
Explanation: 1×2³ + 0×2² + 1×2¹ + 1×2⁰ = 8 + 0 + 2 + 1 = 11.
2. What is the binary representation of the decimal number 25?
A) 11001₂
B) 10101₂
C) 11010₂
D) 10011₂
Answer: A
Explanation: 25 = 16 + 8 + 1 = 2⁴ + 2³ + 2⁰ = 11001₂.
,3. What is the hexadecimal equivalent of the binary number 1111 1010₂?
A) FA₁₆
B) F9₁₆
C) EB₁₆
D) AF₁₆
Answer: A
Explanation: 1111 = F, 1010 = A. Therefore, 1111 1010₂ = FA₁₆.
4. What is the octal representation of the binary number 101 110₂?
A) 56₈
B) 65₈
C) 46₈
D) 54₈
Answer: A
Explanation: Group in 3s: 101 = 5, 110 = 6. Therefore, 101110₂ = 56₈.
5. Convert the hexadecimal number 2C₁₆ to decimal.
A) 44
B) 42
C) 46
D) 40
,Answer: A
Explanation: 2×16¹ + 12×16⁰ = 32 + 12 = 44.
6. What is the 2’s complement of the 8bit binary number 0000 1010?
A) 1111 0110
B) 1111 0101
C) 1111 0111
D) 1111 1000
Answer: A
Explanation: 1’s complement of 00001010 is 11110101. Add 1: 11110110.
7. What is the range of signed decimal numbers that can be represented with 8 bits in 2’s complement
form?
A) 128 to +127
B) 127 to +128
C) 255 to +255
D) 0 to 255
Answer: A
Explanation: For n bits in 2’s complement, the range is 2ⁿ⁻¹ to +2ⁿ⁻¹ 1. For n=8: 128 to +127.
8. What is the BCD representation of the decimal number 47?
, A) 0100 0111
B) 0100 1011
C) 0010 1111
D) 0101 0111
Answer: A
Explanation: 4 = 0100, 7 = 0111. Therefore, 47₁₀ = 0100 0111 in BCD.
9. Convert the Gray code 1011 to binary.
A) 1101
B) 1010
C) 0110
D) 1100
Answer: A
Explanation: Binary bit 3 = Gray bit 3 = 1. Binary bit 2 = 1⊕0 = 1. Binary bit 1 = 1⊕1 = 0. Binary bit 0 =
0⊕1 = 1. Result: 1101₂.
10. What is the decimal value of the 2’s complement number 1111 1100?
A) 4
B) 3
C) 2
D) 1
Answer: A