Binary Coded Decimal (BCD) — Digit Representation In BCD coding, each decimal digit 0 through 9 is represented by which type of binary code width?

Introduction / Context:
BCD is used when decimal digit integrity matters, such as in financial displays and calculators. Each digit is encoded independently, simplifying decimal correction and display driving at the expense of storage efficiency compared to pure binary.

Given Data / Assumptions:

• BCD encodes digits 0..9 individually.
• Standard BCD uses four bits per digit, producing values 0000..1001 for 0..9.
• Invalid combinations 1010..1111 do not represent decimal digits in straight BCD.

Concept / Approach:
The width per digit equals the number of bits required to represent the set of ten symbols. Four bits provide 16 combinations, enough to hold 10 valid codes and 6 invalid ones in straight BCD.

Step-by-Step Solution:
1) Determine required combinations: at least 10.2) Evaluate 2^3 = 8 (insufficient), 2^4 = 16 (sufficient).3) Adopt 4-bit codes for each decimal digit.4) Result: each digit in BCD is a 4-bit binary code.

Verification / Alternative check:
Examine common BCD tables: 0=0000, 1=0001, 2=0010, ..., 9=1001; codes 1010..1111 are unused in straight BCD.

Why Other Options Are Wrong:

• 8-bit and 16-bit: Overkill for a single digit and not standard for BCD.
• ASCII code: ASCII is a 7 or 8 bit character encoding, not a numeric digit code in BCD sense.

Common Pitfalls:
Confusing packed BCD storage (two digits per byte) with the width per digit; the per digit code remains 4 bits.

Final Answer:
4-bit binary code