Character input method using extended keypad including target character and subsequent character, and computing device performing same

A method of inputting a character to a computing device providing a keypad comprising a plurality of keys, wherein a plurality of characters are assigned to at least one of the plurality of keys, the method comprising:

• sensing a touch input to the keypad;
• displaying an extension keypad, as an extension keypad corresponding to the touched key, comprising a plurality of keys when a predetermined key of the plurality of keys of the keypad is touched, wherein a character string is assigned to each of the plurality of keys, the characters or character strings being different from each other;
• sensing a touch input to the extension keypad;
• and
• inputting a character or character string corresponding to the touched key when a predetermined key of the plurality of keys of the extension keypad is touched,
• wherein the inputting of the character or character string comprises:
• when a key to which a predetermined first target character of the extension keypad is assigned is touched, and then the touch is released, inputting the first target character;
• and
• when the key to which the first target character of the extension keypad is assigned is touched, a key to which a predetermined first subsequent character is assigned is touched, and then the touch is released, inputting a character string consisting of the first target character and the first subsequent character in this order.