other logic operations are called arith-
metical units(or arithmetic sections).
(For more information about computers
and math, see “Math in Computing.”)
ALL ABOUT
NUMBERS
What is a number?
The term numbercan be defined in many
ways, including a sizable collection of
people or things, and even an indefinite
quantity or collection. In mathematics a
number, or numeral, is usually defined as
a symbolic representation of a specific
quantity or place in a sequence; to most
people, the most familiar numbers are 1,
2, 3, 4, 5, and so on.
What is a decimal system?
The decimal systemuses the base 10 notation system to represent real numbers. A
decimal expansionis the expression of a number within the decimal system, such as
1, 15, 359, 18.7, and 3.14159. Each number within the system is called a decimal digit.
(Such decimal notation—or a numbering notation based on decimals—was first used
in India around the year 594.) The decimal pointis represented by a period placed to
the right of a unit’s place in a decimal number. It is interesting to note that a comma
is used in continental Europe to denote a decimal point, such as 3,25 (translated as
3.25), which in this case would logically be called the decimal comma.
What is currently the most common numeration system?
The most common numeration system in use today is the Hindu-Arabic. This set of
numerals has ten digits in a place value decimal system, which is a fancy way of saying
that a decimal system—one based on tens—is an integral part of the system and that
each number has a certain value depending on its place in the list of numbers.
How did the Hindu-Arabicnumerals spread to Europe?
Hindu-Arabic numerals (often less accurately called Arabic numerals or numbers) had
their roots in India before 300 BCE. From there, the use of Indian numerals followed the 69
MATH BASICS
Computers have become such an everyday part of
our lives that we hardly think about them. Yet the
mathematical concepts that lie behind their opera-
tions are staggering. Taxi/Getty Images.