Example: "To use the numeric keypad as arrow keys, turn Num Lock off."
Num Lock is a toggle key that toggles the input of the numeric keypad. When Num Lock is on, the keypad can be used to enter numeric values. When Num Lock is off, they keys provide different input. For example, 4 is left arrow, 6 is right arrow, 8 is up arrow, and 2 is down arrow.
Since most keyboards now include arrow keys, the Num Lock is rarely used. However, some keyboards still support the Num Lock feature. Therefore, if you cannot enter numbers with the numeric keypad, you may be able to fix the problem by simply pressing the Num Lock key.