Number base conversion principle: Is “repeated division-by-10” the standard manual technique to convert a decimal (base-10) number to its binary (base-2) representation?

Difficulty: Easy

Correct Answer: Incorrect — use repeated division by 2 for decimal→binary

Explanation:


Introduction / Context:
Converting numbers between bases is a foundational digital-logic and computer-architecture skill. For decimal (base 10) to binary (base 2) conversion, there is a well-known manual “short division” procedure. This question checks whether repeated division by 10 is the correct approach for decimal-to-binary conversion.



Given Data / Assumptions:

  • Source base: 10 (decimal).
  • Target base: 2 (binary).
  • We are discussing the standard manual algorithm for integer conversion.
  • No calculators or programming, just algorithmic steps.


Concept / Approach:
The standard method for converting an integer N from decimal to binary uses repeated division by the target base (2). At each step, you note the remainder (0 or 1), then divide the quotient by 2 again. After the quotient becomes zero, the binary digits are the remainders read in reverse order. Division by 10 is unrelated to producing base-2 digits and would not yield correct binary bits.



Step-by-Step Solution:

Initialize with N (decimal integer).Compute r0 = N mod 2; set N0 = floor(N / 2).Repeat: ri = Ni mod 2; Ni+1 = floor(Ni / 2) until Ni = 0.Binary result = sequence r_last … r2 r1 r0 (remainders read backwards).


Verification / Alternative check:
Try N = 13: 13/2 → q=6 r=1; 6/2 → q=3 r=0; 3/2 → q=1 r=1; 1/2 → q=0 r=1. Reading remainders backward yields 1101, which is correct for 13. Any attempt to divide by 10 produces decimal digits, not binary bits.



Why Other Options Are Wrong:

“Division by 10”: Produces decimal digits, not binary bits.“Repeated subtraction of powers of 10”: Also tied to base 10, not base 2.“Only repeated multiplication by 2 works”: Multiplication by 2 is used for fractional binary; integers use division by 2.


Common Pitfalls:
Mixing up methods for integer vs. fractional parts; forgetting to reverse the remainder sequence; dropping leading zeros in fixed-width formats without considering word size.


Final Answer:
Incorrect — use repeated division by 2 for decimal→binary

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