Difficulty: Medium
Correct Answer: A-2, B-1, C-4, D-3
Explanation:
Introduction / Context:Digital design frequently requires base conversions between octal, decimal, and hexadecimal. This problem tests the ability to convert octal numbers to their hexadecimal forms accurately and then perform a correct matching.
Given Data / Assumptions:
Concept / Approach:
Convert octal to decimal, then decimal to hexadecimal. Alternatively, group binary triples for octal and quadruples for hex; however, the decimal bridge is straightforward and less error-prone for small values.
Step-by-Step Solution:
A: 66 (oct) = 68 + 6 = 48 + 6 = 54 (dec) = 0x36 (hex) ⇒ A-2.B: 77 (oct) = 78 + 7 = 56 + 7 = 63 (dec) = 0x3F (hex) ⇒ B-1.C: 55 (oct) = 58 + 5 = 40 + 5 = 45 (dec) = 0x2D (hex) ⇒ C-4.D: 47 (oct) = 48 + 7 = 32 + 7 = 39 (dec) = 0x27 (hex) ⇒ D-3.Verification / Alternative check:
Binary method: 66(oct) → 110 110(b) → 0011 0110(b) = 0x36; 77(oct) → 111 111(b) → 0011 1111(b) = 0x3F; 55(oct) → 101 101(b) → 0010 1101(b) = 0x2D; 47(oct) → 100 111(b) → 0010 0111(b) = 0x27.
Why Other Options Are Wrong:
Any alternative pairing misrepresents at least one conversion and fails a quick decimal cross-check.
Common Pitfalls:
Arithmetic slips with base-8 multiplication, or confusing the hex pairs (e.g., mixing 0x2D and 0x27).
Final Answer:
A-2, B-1, C-4, D-3
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