In hexadecimal notation, how many different numbers can be represented by a single digit?

In hexadecimal notation, numbers are represented using a base of 16. This number system includes the digits from 0 to 9, which represent values zero through nine, as well as the letters A through F, which represent values ten through fifteen.

Consequently, when considering a single hexadecimal digit, it can represent a total of 16 distinct values:

• The digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 account for the first ten values, and
• The letters A, B, C, D, E, and F add six more values (10-15).

Thus, a single digit in hexadecimal can represent any number from 0 to 15, which totals 16 different numbers. Therefore, the correct answer is 16.