Difficulty: Easy
Correct Answer: A-4, B-3, C-1, D-2
Explanation:
Introduction / Context:Digital systems frequently require quick translation between decimal and binary. This problem reinforces binary conversion for common values, ensuring confidence when reading registers, bitmaps, or instruction encodings.
Given Data / Assumptions:
Concept / Approach:
Convert each decimal number to binary using successive division by 2 or by decomposing into powers of 2. Then match to the list of 8-bit patterns.
Step-by-Step Solution:
A: 45 = 32 + 8 + 4 + 1 = 0010 1101 → 00101101 ⇒ item 4.B: 90 = 64 + 16 + 8 + 2 = 0101 1010 → 01011010 ⇒ item 3.C: 180 = 128 + 32 + 16 + 4 = 1011 0100 → 10110100 ⇒ item 1.D: 210 = 128 + 64 + 16 + 2 = 1101 0010 → 11010010 ⇒ item 2.Verification / Alternative check:
Hex cross-check: 45 = 0x2D = 0010 1101; 90 = 0x5A = 0101 1010; 180 = 0xB4 = 1011 0100; 210 = 0xD2 = 1101 0010. Hex-to-binary mapping confirms the 8-bit strings.
Why Other Options Are Wrong:
Each incorrect option mis-assigns at least one decimal-to-binary mapping, which will break in arithmetic or bit-test verification.
Common Pitfalls:
Dropping leading zeros (acceptable visually but confusing in fixed-width contexts) or mixing nibble order when transcribing hex to binary.
Final Answer:
A-4, B-3, C-1, D-2
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