Hexadecimal to decimal — evaluate 777₁₆. Compute the decimal value of the hex number 0x777 using positional weights.

Difficulty: Easy

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 = 1911

Verification / 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

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