ALU 101 Binary Number Systems 1 — Questions and Answers
Question 1: What is the decimal equivalent of the binary number 1011?
- 9
- 10
- 11 (Correct answer)
- 13
Correct answer: 11
1011 in binary = 1×8 + 0×4 + 1×2 + 1×1 = 8 + 0 + 2 + 1 = 11 in decimal.
Question 2: How many bits are required to represent the decimal number 255?
- 6
- 7
- 8 (Correct answer)
- 9
Correct answer: 8
255 = 2⁸ − 1, so 8 bits are needed to represent it (11111111 in binary).
Question 3: What is the hexadecimal representation of the binary number 11001010?
- CA (Correct answer)
- AC
- CF
- FA
Correct answer: CA
Splitting 11001010 into nibbles gives 1100 (C) and 1010 (A), so the hex value is CA.
Question 4: In the two's complement system, what is the two's complement of 0101 (4-bit)?
- 1010
- 1011 (Correct answer)
- 0110
- 1001
Correct answer: 1011
Invert 0101 to get 1010, then add 1 to get 1011, which is the two's complement of 0101.
Question 5: Which number base is most commonly used internally by ALU hardware?
- Decimal (base 10)
- Octal (base 8)
- Binary (base 2) (Correct answer)
- Hexadecimal (base 16)
Correct answer: Binary (base 2)
ALUs operate internally on binary (base 2) data because digital circuits use two voltage states representing 0 and 1.
Question 6: What is the decimal value of the hexadecimal number 0xFF?
- 128
- 255 (Correct answer)
- 256
- 512
Correct answer: 255
0xFF = 15×16 + 15 = 240 + 15 = 255 in decimal.
ALU 101 Binary Number Systems 1
What is the decimal equivalent of the binary number 1011?