Hexadecimal to decimal — evaluate 777₁₆. Compute the decimal value of the hex number 0x777 using positional weights.
Electronics
Number Systems and Codes
Difficulty: Easy
Choose an option
-
A191
-
B1911
-
C19
-
D19111
-
E2071
Answer
Correct Answer: 1911
Explanation
Introduction / Context:Hexadecimal expands by powers of 16. Rewriting multi-digit hex numbers into decimal clarifies positional weighting and strengthens mental math for address offsets and constants in code.
Given Data / Assumptions:
- Hex number: 777₁₆
- Each digit 7 represents decimal 7
Concept / Approach:Apply place values: value = d216^2 + d116^1 + d016^0. With d2=d1=d0=7, the computation is straightforward.
Step-by-Step Solution:
16^2 = 256 ⇒ 7256 = 179216^1 = 16 ⇒ 716 = 11216^0 = 1 ⇒ 71 = 7Sum: 1792 + 112 + 7 = 1911Verification / Alternative check:Convert to binary: 7 → 0111, so 777₁₆ = 0111 0111 0111₂. Evaluate in decimal: (4+2+1)16^2 + (4+2+1)16 + (4+2+1) = 7256 + 716 + 7, same result 1911₁₀.
Why Other Options Are Wrong:
- 191 and 19: undercount by ignoring higher place values.
- 19111: overcount by an extra digit place.
- 2071: arithmetic mismatch of the 16-based expansion.
Common Pitfalls:
- Treating base-16 digits as base-10 and adding 7+7+7=21 (incorrect).
Final Answer:1911