The ‘Num Lock’ button is usually located over by the keypad on the right side of the keyboard. What’s it for? Well it locks the number functions on the keypad. When ‘Num Lock’ is on, using the keypad will produce the numeric functions (0-9, .). With ‘Num Lock’ turned off, you have access to the navigation keys on the keypad (Home, End, PgUp, PgDn, arrow keys, delete, insert). So next time you use your keypad and get an unexpected result, check ‘Num lock’!