Binary subtraction check – is 1011 (base 2) minus 0111 (base 2) equal to 1000 (base 2)?

Difficulty: Easy

Correct Answer: Incorrect

Explanation:


Introduction / Context:
This problem verifies binary subtraction accuracy. As with decimal, you may subtract bit-by-bit with borrows or convert to two’s-complement addition for a systematic approach. We compare the given claim to the computed result.


Given Data / Assumptions:

  • Operands: 1011 (11 decimal) and 0111 (7 decimal).
  • Unsigned comparison; no modular wrap unless explicitly specified.
  • Goal: test if the difference equals 1000.


Concept / Approach:
Compute 11 − 7 = 4 (decimal). The correct binary for 4 is 0100 (or simply 100). The proposed 1000 equals 8 (decimal), which is not the correct difference. Therefore, the statement is false.


Step-by-Step Solution:

1) Decimal sanity: 11 − 7 = 4.2) Binary: 1011 − 0111. Subtract bitwise with borrows: result 0100.3) Compare with claim: 1000 (8 decimal) ≠ 0100 (4 decimal).4) Conclusion: the equality is incorrect.


Verification / Alternative check:
Two’s complement: 1011 + (two’s complement of 0111 = 1001) = 10100. Discard carry beyond 4 bits → 0100, matching the direct subtraction result, so 4 is confirmed.


Why Other Options Are Wrong:
Borrow inhibition or signed mode does not make 11 − 7 equal 8. Modulo wrap would require a specified fixed width and still would not yield 1000 as the canonical result here.


Common Pitfalls:
Mixing up borrow steps or misaligning bits. Always line up bits and track borrows carefully.


Final Answer:
Incorrect

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