Difficulty: Easy
Correct Answer: 15
Explanation:
Introduction / Context:Octal (base 8) is another positional number system. Although less common today than hexadecimal, it appears in legacy systems and permissions in Unix-like operating systems. Converting small octal numbers to decimal is straightforward and reinforces the concept of place value.
Given Data / Assumptions:
Concept / Approach:For an octal number d1 d0, the decimal value is d1 * 8^1 + d0 * 8^0. Here, 1 is the “eights” place and 7 is the “ones” place. Ensure digits are within the octal range (0–7); digit 8 would be invalid in octal notation.
Step-by-Step Solution:
1) Identify place values: 8^1 = 8, 8^0 = 1.2) Multiply digits: 1 * 8 + 7 * 1 = 8 + 7.3) Sum: 8 + 7 = 15 decimal.4) Therefore, 17₈ = 15₁₀.Verification / Alternative check:Cross-check via binary: 17₈ = 001 111₂ = 15 decimal, confirming the result.
Why Other Options Are Wrong:
Common Pitfalls:Interpreting “17” as base 10 or assuming octal digits can include “8” or “9”.
Final Answer:15
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