What is the purpose of the Number Lock button on computer keyboards?

Question

What is the purpose of the Number Lock button on computer keyboards? Besides of course to annoy you when it accidentally gets pushed and you think you are typing all these numbers and then you look up at the screen and nothing has actually happened. Is there an actual practical purpose or no?

Answer 1

num lock allows you to use the number pad or not if you wanna use it turn it on (green led lights up) if not turn it off.

Answer 2

As an Accountant, it's for the 10 key. When you hear an Accountant say that F word, it's because the number lock is off.  

Answer 3

You can use the numpad to move the cursor around after turning the mouse keys on in Accessibility options in the Control Panel

Answer 4

It changes the values returned by the num pad. It is very useful for rapidly scanning through text with the num lock disabled.