Integers
Theintegersare the set ofwhole numbersand their opposites.Fractionsanddecimalsare not included in the set of integers.
For example,andare all integers.
The numbers such asandare not integers.
(Note that a number can be an integer even if it is written as a decimal or a fraction: for example,andare both integers, because they are equal toand, respectively.)
Thesetof integers is usually represented by the symbol .
We can plot the integers as equally spaced points on anumber line, as shown in the figure. The arrows at the left and right sides show that the integers continue forever in both directions.
The whole numbers greater thanare calledpositive integers. Their opposites, which are less than, are callednegative integers. Zero is neither positive nor negative.
If two numbers are opposite, they are the same distance away from zero. For example,andare opposites, and each isunits from zero.
The sum, difference, or product of two integers is an integer. For example,
Sum:
Difference:
Product:
The quotient of two integers is not always an integer.
For example,is an integer because it divides evenly.
However,is not an integer. When a quotient of integers does not divide evenly, the result is afraction.
Example:
Which of the following numbers is an integer?
is greater than the integerand less than the integer. Theat the end of the number indicates a fractional part. So, this is not an integer.
The numberhas a square root sign; its value is greater than the integerbut less than the integer. Sinceis not a perfect square likeor,is not an integer.
The numberis a fraction greater thanbut less than, so this is not an integer.
The numberis in the set.
So,is an integer.