Use keyboard function keys on Mac
Most function keys on your keyboard serve as specific control keys, such as volume and brightness controls.
However, apps may also assign alternative functions to these same keys. For example, on some keyboards Exposé uses F9 and F10 to perform special actions. Some computers allow you to use the alternative function assigned to a function key by pressing and holding the Function (Fn) key as you press a function key.
If you frequently use the alternative function of a function key, you can switch the keyboard so that the function keys perform the alternative function without you having to press Fn. When this option is selected, press and hold Fn as you press a function key to use a function key’s original hardware control function. If your keyboard doesn’t have an Fn key, try pressing and holding the Control key.
On your Mac, choose Apple menu > System Preferences, click Keyboard, then click Keyboard.
Select “Use F1, F2, etc. keys as standard function keys.”
To use the numeric keypad on your keyboard, press the Num Lock key. The other letter keys are disabled and only the keys on the numeric keypad work. Press Num Lock again to return the keyboard to its normal state.
If your Mac doesn’t have a numeric keypad, the U, I, O, J, K, L, and M keys may have numbers on them. Press the Fn key as you press these letter keys to use them as a numeric keypad.