Number systems refresher The base-10 (decimal) number system is composed of how many distinct symbols (digits)?

Introduction / Context:
Understanding different bases is central to digital electronics and computing. Decimal (base 10) is the everyday system; binary (base 2), octal (base 8), and hexadecimal (base 16) are used heavily in engineering. This question checks recall of the decimal system’s symbol count.

Given Data / Assumptions:

• Decimal uses symbols 0 through 9.
• Base b systems use exactly b distinct digit symbols.
• No extended notation (like letters for digits beyond 9) applies to base 10.

Concept / Approach:
By definition, a base-10 system has ten unique symbols. Positional notation means each position weight is a power of 10, and digits 0–9 are used to represent quantities at each position.

Step-by-Step Solution:

Verification / Alternative check:
Conversion methods (e.g., repeated division) and place-value representation rely on exactly ten symbols in decimal arithmetic; elementary math supports this definition unequivocally.

Why Other Options Are Wrong:

• 2: Binary, not decimal.
• 8: Octal, not decimal.
• 16: Hexadecimal, not decimal.
• 20: Not a standard base in common digital practice and certainly not decimal.

Common Pitfalls:
Confusing the count of symbols with the largest symbol value; remember the highest digit is 9, but the number of symbols is 10 total.

Final Answer:
10