Num lock

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Num Lock is a key on the numeric keypad of most computer keyboards, used to switch the pad between number entry and arrow keys. 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 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.

These days since many computers have a full-size keyboard, 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 a function shift button Fn; 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.

Num Lock is also used in standard BIOS for extra input.

[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
IBM/Windows keyboard (US layout)
v • d • e
Esc F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 PrtSc ScrLk Pause
Tilde Exclamation mark At sign Number sign Dollar sign Percent sign Caret Ampersand Asterisk Bracket Bracket Underscore Plus and minus signs Backspace Grave accent 1 (number) 2 (number) 3 (number) 4 (number) 5 (number) 6 (number) 7 (number) 8 (number) 9 (number) 0 (number) Hyphen Equals sign Backspace Tab key Q W E R T Y U I O P Bracket Bracket Vertical bar Tab key Q W E R T Y U I O P Bracket Bracket Backslash Caps lock A S D F G H J K L Colon (punctuation) Quotation mark Enter key Caps lock A S D F G H J K L Semicolon Apostrophe Enter key Shift key Z X C V B N M Bracket Bracket Question mark Shift key Shift key Z X C V B N M Comma (punctuation) Full stop Slash (punctuation) Shift key Control key Windows key Alt key Space bar AltGr key Windows key Menu key Control key
Ins Home PgUp NumLk / * -
Del End PgDn 7 8 9 +
4 5 6
↑ 1 2 3 Ent
← ↓ → 0 .
v • d • e
Keyboard keys
Dead keys
Modifier keys
Control · Shift · Alt/Option (Apple) · AltGr · Command/Meta (Apple/MIT/Sun keyboards) · Windows · Super · Hyper · Fn (compact keyboards)
Lock keys
Scroll lock · Num lock · Caps lock
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