# Definition
The period of a fraction is the digits that repeat themselves.

The digits can be from $0-9$, and the length of the period is determined by the denominator, n in $\frac{a}{n}$ .
# Examples
$\frac{22}{7}= 3.142857142857\dots$ where the period here is $142857$ and has a length 6
$\frac{1}{2} = 0.5000000\dots$ has the period $0$, with the length being 1.