How many digits are present in the whole number system?

The whole number system consists of ten unique digits, which are 0 through 9. This base-10 (decimal) number system forms the foundation for counting and arithmetic in mathematics. Each digit can represent different values depending on its position in a number, which is known as its place value.

In contrast, options suggesting fewer or more than ten digits are incorrect because they do not account for the complete range of numeric characters used in standard numerical representations. For example, an eight-digit system would not adequately allow for all the numbers we use in everyday counting, while twelve or sixteen digits exceed the recognized set in the decimal system. Therefore, the correct answer reflects that there are indeed ten digits in the whole number system.