Num Lock

Num Lock or Number Lock (⇭) is a key on the numeric keypad of most computer keyboards. It is a lock key, like Caps Lock and Scroll Lock. Its state affects the function of the numeric keypad commonly located to the right of the main keyboard and is commonly displayed by an LED built into the keyboard.

A keyboard with Num Lock turned on as indicated by a LED

The Num Lock key exists because earlier 84-key IBM PC keyboards did not have cursor control or arrows separate from the numeric keypad. Most earlier computer keyboards had different number keys and cursor control keys; however, to reduce cost, IBM chose to combine the two in their early PC keyboards. Num Lock would be used to select between the two functions. On some laptop computers, the Num Lock key is used to convert part of the main keyboard to act as a (slightly skewed) numeric keypad rather than letters. On some laptop computers, the Num Lock key is absent and replaced by the use of a key combination.

Since Apple keyboards never had a combination of arrow keys and numeric keypad (but some lacked arrow keys, function keys, and a numeric keypad altogether), Apple has keyboards with a separate numeric keypad but no functional Num Lock key. Keyboards manufactured by Apple will instead use a Clear key but not all Apple manufactured keyboards will be provided with it.

Numeric keypad

Keys affected by Num Lock

Key on Numeric Keypad	Num Lock On	Num Lock Off
1	1	End
2	2	Down Arrow
3	3	Page Down
4	4	Left Arrow
5	5	does nothing (usually)
6	6	Right Arrow
7	7	Home
8	8	Up Arrow
9	9	Page Up
0	0 (zero or comma)	Insert
.	. (dot) or , (comma)	Delete

IBM PC keyboard (Windows, ANSI US layout)
Esc		F1	F2	F3	F4		F5	F6	F7	F8		F9	F10	F11	F12		PrtScn/ SysRq	Scroll Lock	Pause/ Break
																	Insert	Home	PgUp		Num Lock	∕	∗	−
																	Delete	End	PgDn		7	8	9
																					4	5	6
																		↑			1	2	3	Enter
																	←	↓	→		0    Ins		.  Del

References

ow Num Lock Works Numeric Mode: When Num Lock is turned on, the keys on the numeric keypad can be used to input numbers and mathematical symbols, much like a calculator. This mode is particularly useful for data entry tasks that involve a lot of numerical input.

Cursor Control Mode: When Num Lock is turned off, the numeric keypad functions like the arrow keys. This allows the user to navigate the cursor around the screen using the numeric keypad.

Typical Keys on Numeric Keypad Numbers 0-9: Standard digits for numerical input.

Decimal Point: A dot used for decimal numbers.

Mathematical Operators: Includes addition ( ), subtraction (-), multiplication (*), and division (/).

Enter Key: Allows for quick entry of numbers or commands.

LED Indicator Most keyboards have an LED indicator light that shows whether Num Lock is activated. This helps users quickly see the current state of the key without having to press it.

Common Uses Data Entry: Ideal for accountants, cashiers, and others who frequently enter numerical data.

Gaming: Some games use the numeric keypad for additional controls.

Navigation: Useful for controlling the cursor in text documents or spreadsheets when Num Lock is off.

Whether you’re crunching numbers or navigating through documents, Num Lock ensures that the numeric keypad serves dual purposes, enhancing your efficiency and functionality.