Perhaps reading about it will help?

p-adic Expansions

HugeDomains.com - Shop for over 350,000 Premium Domains (A Tutorial on p-adic Arithmetic C¸ . K. Ko¸c Electrical & Computer Engineering Oregon State University Corvallis, Oregon 97331 Technical Report, April 2002) It's a .pdf file

p-adic Number -- from Wolfram MathWorld