Turning Num Lock on and off depends on the computer model.  Some computers use the <Num Lock> key, others use the <FN>+<Num Lock> keys.

For more information on Num Lock, see the Online User's Guide.

To set this option, perform the following:

1. Enter the BIOS or System Setup by pressing the <F2> key at the Dell screen.
2. Using the arrow keys, set Enable Keypad to By Numlock.