Binary subtraction basics Compute the result of 111₂ − 001₂ and express the answer in binary.

Difficulty: Easy

Correct Answer: 110

Explanation:


Introduction / Context:
Binary subtraction mirrors decimal subtraction but with base 2. Recognizing basic patterns such as subtracting 1 from a number simplifies mental computation and checking of results.


Given Data / Assumptions:

  • Minuend: 111₂ (which equals 7 decimal).
  • Subtrahend: 001₂ (which equals 1 decimal).
  • No borrow issues across more than one bit in this simple case.


Concept / Approach:
Since 111₂ is all ones, subtracting 001₂ simply clears the LSB and leaves the higher bits unchanged, equivalent to 7 − 1 = 6 decimal. Convert back to binary after subtraction to confirm.


Step-by-Step Solution:

1) Convert: 111₂ → 7₁₀, 001₂ → 1₁₀.2) Subtract in decimal: 7 − 1 = 6.3) Convert 6 to binary: 6 = 4 + 2 = 2^2 + 2^1 → 110₂.4) Therefore, 111₂ − 001₂ = 110₂.


Verification / Alternative check:
Perform column-wise binary subtraction: from right to left, 1−1=0; next bits 1−0=1; next 1−0=1 → 110.


Why Other Options Are Wrong:

  • 100: equals 4, not 6.
  • 111: equals the original minuend (no subtraction performed).
  • 001: equals 1, the subtrahend.


Common Pitfalls:
Attempting unnecessary borrows when subtracting 1 from an odd number ending in 1.


Final Answer:
110

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