When Num Lock is off, keys 8, 6, 2, and 4 act like arrow/navigation keys up, right, down, and left; and 7, 9, 3, and 1 act like Home, PgUp, PgDn, and End, respectively. When Num Lock is on, digit keys produce the corresponding digit. On Apple Macintosh computers, which lack a Num Lock key, the numeric keypad always produces only numbers; the Num Lock key is replaced by the Clear key.