Know Your Numbers
The SAT loves to throw around terminology about numbers.
If you don’t know the terminology, you won’t know how to answer
the question.
- Whole Numbers. The set of counting
numbers, including zero {0, 1, 2, 3, . . .}.
- Natural Numbers. The set of all whole positive
numbers except zero {1, 2, 3, 4, 5, . . .}.
- Integers. The set of all positive and negative
whole numbers, including zero. Fractions and decimals are not included
{. . . , –3, –2, –1, 0, 1, 2, 3, . . .}.
- Rational Numbers. The set of all numbers
that can be expressed as integers in fractions. That is, any number
that can be expressed in the form m⁄n,
where m and n are integers.
- Irrational Numbers. The set of all numbers
that cannot be expressed as integers in a fraction. Examples include
π,
, and 1.01001000100001000001. . . . A number
must be either rational or irrational; no number can be both.
- Real Numbers. Every number on the number
line. The set of real numbers includes all rational and irrational
numbers.
