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Num Lock

Num Lock is a key that is typically located near the keypad on the right side of a keyboard. Like Caps Lock, Num Lock is a toggle key, which toggles the input of certain keys, depending whether Num Lock is on or off.

Num Lock is short for "Number Lock." It was implemented in early Windows keyboards to lock the input of the numeric keypad. When Num Lock is on, the keypad only enters numbers. When Num Lock is off, the keys may provide different input as indicated below:

  • . - Delete
  • 0 - Insert
  • 1 - End
  • 2 - Down Arrow
  • 3 - Page Down
  • 4 - Left Arrow
  • 5 - Clear
  • 6 - Right Arrow
  • 7 - Home
  • 8 - Up Arrow
  • 9 - Page Up
Since early PC keyboards did not have arrow keys, Num Lock gave the keypad a useful dual functionality. However, now that most keyboards have arrow keys and other special keys, such as Page Up and Page down, the Num Lock key is not often used. On some keyboards (especially Macintosh keyboards), the Num Lock is not functional. On others, it typically is set to ON by default.

While you may not need to use the Num Lock key with your keyboard, it is helpful to know the key's function. If you find yourself trying to enter numbers with the numeric keypad and nothing appears on the screen, it is possible that Num Lock is OFF. If this is the case, pressing the Num Lock key should fix the problem.

Tech Factor:
Updated: October 15, 2009
Category: Technical Terms