Which option best describes what a digit represents?

A digit represents a value in a numeral system. It is a symbol used to denote a specific quantity and can range from 0 to 9 in the base-10 system, which is the most widely used numeral system. For instance, the digit 5 represents the quantity five, while the digit 3 represents the quantity three. In larger numbers, digits hold positions that contribute to the overall value of the whole number, influenced by their placement (units, tens, hundreds, etc.).

The other choices do not accurately reflect the nature of a digit. "Synonym" does not relate to the numerical function of a digit, as it pertains to words with similar meanings rather than numerical representations. Likewise, a digit itself does not represent a fraction, though fractions can be formed using digits. Lastly, while digits can be involved in measurements (such as when representing distances or weights), a digit itself is not a measurement; it simply denotes a value that can be part of a measurement. Thus, framing a digit as primarily a value captures its essential role in mathematics and numeral systems.