# rational number

In mathematics rational means "ratio like." So a **rational number** is one
that *can be* written as the ratio of two integers.
For example 3=3/1, −17,
and 2/3 are rational numbers.

Most real numbers (points on the number-line)
are irrational (not rational). The rational numbers are those which have
repeating decimal expansions (for example 1/11=0.09090909..., and
1=1.000000...=0.999999...). They are also those which have terminating continued
fraction expansions. Finally, the real number *x* is rational if and only if
there are finitely many solutions to | *x* − *a*/*b* | <
1/*b*^{2}.

**See Also:** IrrationalNumber, AlgebraicNumber

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