Binary arithmetic: What is the 1's complement (bitwise inversion) of the two-bit binary number 10?
Computer Science
Computer Fundamentals
Difficulty: Easy
Choose an option
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A01
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B11
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C110
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D10
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ENone of the above
Answer
Correct Answer: 01
Explanation
Introduction / Context:In digital logic, the 1's complement of a binary value is obtained by flipping every bit: zeros become ones and ones become zeros. It is a foundational operation in binary arithmetic, checksums, and two's-complement negation steps.
Given Data / Assumptions:
- Number: '10' in binary, explicitly two bits long.
- Operation: 1's complement (bitwise NOT), not two's complement.
Concept / Approach:
Apply inversion to each bit independently. For a two-bit pattern, the left bit and right bit are processed the same way: 1 becomes 0, 0 becomes 1.
Step-by-Step Solution:
Write the original two-bit number: 1 0.Invert each bit: 1 → 0, 0 → 1.Concatenate the results to get 0 1, i.e., '01'.Verification / Alternative check:
Using logical NOT (~) at the bit level confirms: ~(10₂) = 01₂ when the width is fixed at two bits.
Why Other Options Are Wrong:
- 11: flips only the last bit incorrectly.
- 110: changes bit-width; not permitted for a two-bit representation.
- 10: unchanged; not a complement.
- None of the above: incorrect because '01' is correct.
Common Pitfalls:
- Confusing 1's complement with 2's complement (which adds 1 after inversion).
- Accidentally changing the number of bits during the operation.
Final Answer:
01.