1. A method for entering a character from a set of characters in a device having a keypad with a plurality of keys and a display, said method comprising: selecting a first index according to a received key input value; selecting a second index according to the number of times the key input value has been sequentially entered; selecting an assignment matrix, having a plurality of matrix elements, according to a sequence of previously entered characters; retrieving a matrix element from said assignment matrix according to said first and second indices; displaying a selected character corresponding to said matrix element on said display; and entering said selected character when a key specified as an enter key is activated, wherein the order of the plurality of matrix elements in said assignment matrix is determined by a probability that a corresponding character will be the next to be entered.