Base conversion — convert the octal number to decimal. Task: Find the decimal value of 74₈ by expanding with powers of 8.

Difficulty: Easy

Correct Answer: 60

Explanation:

Introduction / Context:Octal (base 8) is often used as a compact representation of binary. Converting octal to decimal reinforces understanding of positional weights based on powers of 8.

Given Data / Assumptions:

  • Octal number: 74₈
  • Digits: 7 and 4 (valid octal digits 0–7)

Concept / Approach:Expand using positional weights: the left digit is multiplied by 8^1 and the right digit by 8^0, then sum the results to get the decimal value.

Step-by-Step Solution:

8^1 = 8, 8^0 = 1Compute: 78 + 41 = 56 + 4Total = 60

Verification / Alternative check:Convert 74₈ to binary: 7 → 111, 4 → 100; combined 111100₂ = 60₁₀, confirming the same result.

Why Other Options Are Wrong:

  • 74: confuses the symbol with its base-10 interpretation.
  • 22, 62, 58: incorrect arithmetic of octal expansion.

Common Pitfalls:

  • Including digits 8 or 9 in octal or misapplying decimal weights instead of powers of 8.

Final Answer:60

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion