Editing Number (section)

===''p''-adic numbers===
{{main|p-adic number|l1=''p''-adic number}}
The ''p''-adic numbers may have infinitely long expansions to the left of the decimal point, in the same way that real numbers may have infinitely long expansions to the right. The number system that results depends on what [[radix|base]] is used for the digits: any base is possible, but a [[prime number]] base provides the best mathematical properties. The set of the ''p''-adic numbers contains the rational numbers, but is not contained in the complex numbers.

The elements of an [[algebraic function field]] over a [[finite field]] and algebraic numbers have many similar properties (see [[Function field analogy]]). Therefore, they are often regarded as numbers by number theorists. The ''p''-adic numbers play an important role in this analogy.