The number system most commonly used today is based on the Hindu-Arabic number system, which was developed in what is now India around 300 B.C.E. The Arab mathematicians adopted this system and brought it to Spain, where it slowly spread to the rest of Europe.

The present-day number system, which is called the decimal* or base-10 number system, is an elegant and efficient way to express numbers. The rules for performing arithmetic calculations are simple and straightforward.

*The prefix "decl" In the word "declmal" means ten.

Basic Properties

The decimal number system is based on two fundamental properties. First, numbers are constructed from ten digits, or numerals—0, 1, 2, 3, 4, 5, 6, 7, 8, and 9—that are arranged in a sequence. Second, the position of a digit in the sequence determines its value, called the place value. Because each digit, by its place value, represents a multiple of a power of 10, the system is...