[est1895]

Ever since I owned a PC, I never knew if the Number Lock key, on the keyboard was needed to be selected prior to startup.  What is it for anyway? 

[NeonShivan]

Number Lock key allows the use of the number pad if enabled(?)

[Ghostavo]

It locks the numbers in the numeric keypad, i.e. instead of using the numeric keypad's buttons as other functions, usually arrow signs amongst others, you use it as numbers.

You can activate it and deactivate it during runtime, so it's not something that's needed during startup.

[BloodEagle]

It should be noted that when NUM_LOCK is enabled, holding shift will cause key depressions to ignore the lock; the reverse of this is not true.  This could be kind of useful for Excel work, I guess, maybe.

Also, the only reason to disable it is if it interferes with an application, which is incredibly rare in my experience.  It's kind of vestigial.

[Nuke]

it just sets numlock on be default. turn it off and it will default to off. you can toggle it no matter which you pick.