Base-p expansion
= Base-p expansion
{title2=$k=\sum_{i\ge0}k_ip^i,\quad0\le k_i<p$}
For an integer base $p\ge2$, a nonnegative <integer> has a finite positional representation with digits $k_i\in\{0,\ldots,p-1\}$. Repeated <Euclidean division> gives the digits uniquely; appending zero high-place digits has no effect. The base need not be prime for uniqueness, but a prime base is useful in <Lucas theorem> and modular <binomial coefficients>.