The p-adic numbers were introduced by K. Hensel in 1908 in his book Theorie der algebraïschen Zahlen, Leipzig, 1908. In this article we present a package that does p-adic calculations using Mathematica. It allows addition, subtraction, multiplication, and division of p-adic numbers written in Hensel expansion. Functions, such as sqrt, log, exp, sin, cos, sinh, and cosh, are defined using their power series expansion. We also calculate the coefficients of a continuous function with respect to the Mahler and Vanderput bases, and implement the p-adic Newton method.