Num lock

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Num Lock is a key on the numeric keypad of most computer keyboards. It is a toggle key, like Caps Lock and Scroll Lock. Its state is commonly represented by an LED light built into the keyboard.

The Num Lock key exists because earlier 84-key IBM PC keyboards did not have arrows separate from the numeric keypad. Num Lock would be used to choose between the two functions. On some laptop computers, Num Lock keys are used to convert part of the main keyboard to act as a (slightly skewed) numeric keypad rather than letters.

Since most desktop computers nowadays have a full-size keyboard with both a numpad and separate arrow keys, Num Lock is rarely used for its original purpose, and ends up confusing the user if the computer has for some reason activated or deactivated the Num Lock key without the user being aware of it. This is less of an issue on most laptop computers, since activating the Num Lock function typically requires use of the Fn key; however, if a full-size keyboard is plugged into a laptop keyboard, then the Num Lock function is normally off, and the user would have to activate the Num Lock function to use the numeric keypad for numeric entry. Since Apple keyboards have dedicated arrow keys, Apple keyboards that offer a separate numeric keypad may have no Num Lock key or a non-functional Num Lock key.

[edit] Keys affected by Num Lock

Key Name	Numlock On	Numlock Off
Numpad 1	1	End key
Numpad 2	2	Down Arrow Key
Numpad 3	3	Page Down
Numpad 4	4	Left Arrow Key
Numpad 5	5	Clear Key
Numpad 6	6	Right Arrow Key
Numpad 7	7	Home key
Numpad 8	8	Up Arrow Key
Numpad 9	9	Page Up
Numpad 0	0 (zero) (comma on some keyboard layouts)	Insert key
Numpad .	. (dot)	Delete key