**
Absolute Value
** -
(Positive) distance between a number and zero on the number line; the
corresponding "unsigned" number. | - 4| = 4 and | 4| = 4.

**
Counting Numbers
** -
Also called natural numbers, the set of positive numbers used to count
objects. 1, 2, 3, 4, 5, ...

**
Integers
** -
The set of numbers including all the whole numbers and their opposites (the
positive whole numbers, the negative whole numbers, and zero) -- fractions and
decimals are *not* integers. ... -3, -2, -1, 0, 1, 2, 3, ...

**
Irrational Numbers
** -
The set including all numbers that are non-
terminating, non-
repeating decimals.

**
Natural Numbers
** -
The set of positive numbers used to count objects (also called counting
numbers). 1, 2, 3, 4, 5, ...

**
Negative Numbers
** -
The set of numbers to the left of zero on the number line--numbers less than
zero.

**
Number Line
** -
A horizontal line that has points that correspond to numbers. The points are
spaced according to the value of the number they correspond to; in a number line
containing only whole numbers or integers, the points are equally spaced.

**
Opposite
** -
A number that is the same distance from zero as a given number, but on the
opposite side of zero. For example, 7 and -7 are opposites, and -9 and 9 are opposites.

**
Positive Numbers
** -
The set of numbers to the right of zero on the number line--numbers greater than
zero.

**
Rational Numbers
** -
The set of numbers including all the integers, plus all the
fractions, or terminating
decimals and repeating
decimals.
Every rational number can be
written as a fraction *a*/*b*, where *a* and *b* are integers.

**
Real Numbers
** -
The set of all the rational numbers and all the irrational numbers.

**
Whole Numbers
** -
The set of numbers including all the natural numbers and zero--negative
numbers are *not* whole numbers. 0, 1, 2, 3, 4, ...