Difficulty: Medium
Correct Answer: 18.25
Explanation:
Introduction / Context:
Binary numbers with fractional parts occur in fixed-point arithmetic, digital signal processing, and fractional addressing. Converting such values to decimal requires understanding positional weights on both sides of the binary point.
Given Data / Assumptions:
Concept / Approach:
For a binary string a₄a₃a₂a₁a₀.b₁b₂b₃b₄, the decimal value is Σ aᵢ * 2^i + Σ bⱼ * 2^(−j). Only positions with bit 1 contribute to the sum.
Step-by-Step Solution:
Integer part 10010₂: weights are 2^4=16, 2^3=8, 2^2=4, 2^1=2, 2^0=1.Bits = 1 0 0 1 0 ⇒ contributions 16 + 2 = 18.Fractional part .0100₂: weights are 2^(−1)=0.5, 2^(−2)=0.25, 2^(−3)=0.125, 2^(−4)=0.0625.Bits = 0 1 0 0 ⇒ contribution 0.25 only.Total = 18 + 0.25 = 18.25.
Verification / Alternative check:
Convert the fractional portion by fraction: 0.0100₂ = 1/4 = 0.25. Add to the integer 18 to confirm 18.25. A calculator that accepts binary input or a spreadsheet using powers can reproduce the result exactly.
Why Other Options Are Wrong:
Common Pitfalls:
Final Answer:
18.25
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