Elementary Arithmetic - The Digits

The Digits

Digits are the entire set of symbols used to represent numbers. In a particular numeral system, a single digit represents a different amount than any other digit, although the symbols in the same numeral system might vary between cultures.

In modern usage, the Arabic numerals are the most common set of symbols, and the most frequently used form of these digits is the Western style. Each single digit matches the following amounts:
0, zero. Used in the absence of objects to be counted. For example, a different way of saying "there are no sticks here", is to say "the number of sticks here is 0".
1, one. Applied to a single item. For example, here is one stick: I
2, two. Applied to a pair of items. Here are two sticks: I I
3, three. Applied to three items. Here are three sticks: I I I
4, four. Applied to four items. Here are four sticks: I I I I
5, five. Applied to five items. Here are five sticks: I I I I I
6, six. Applied to six items. Here are six sticks: I I I I I I
7, seven. Applied to seven items. Here are seven sticks: I I I I I I I
8, eight. Applied to eight items. Here are eight sticks: I I I I I I I I
9, nine. Applied to nine items. Here are nine sticks: I I I I I I I I I

Any numeral system defines the value of all numbers which contain more than one digit, most often by addition of the value for adjacent digits. The Hindu–Arabic numeral system includes positional notation to determine the value for any numeral. In this type of system, the increase in value for an additional digit includes one or more multiplications with the radix value and the result is added to the value of an adjacent digit. With Arabic numerals, the radix value of ten produces a value of twenty-one (equal to 2×10 + 1) for the numeral "21". An additional multiplication with the radix value occurs for each additional digit, so the numeral "201" represents a value of two-hundred-and-one (equal to 2×10×10 + 0×10 + 1).

The elementary level of study typically includes understanding the value of individual whole numbers using Arabic numerals with a maximum of seven digits, and performing the four basic operations using Arabic numerals with a maximum of four digits each.