1. A method for assigning large sets of characters in different modes to the keys of a standard numeric keypad for text/data entry on a character-input device comprising: (a) associating each key of the numeric keypad with a first non-numeric character mode and one or more other, optional character modes, wherein the first character mode associated with the key includes a pair of characters of a standard alphabetic character set, and wherein the other, optional character modes associated with the key includes at least another non-numeric character; (b) providing a mode selection key with the numeric keypad for selecting between the first character mode and the other optional character modes; and (c) enabling text/data entry of alphabetic and other characters via the numeric keypad by interpreting a keypress of the mode selection key to select one of the character modes, and interpreting a keypress of a key of the numeric keypad in the first character mode as selecting the first character of the pair and two keypresses in succession as selecting the second character of the pair for that key, whereby the numeric keypad is enabled for text/data entry accommodating the alphabetic characters of a standard alphabetic character set as well as other characters with an average keypress-per-data-entry (KPD) ratio of less than 2.0.