Hi vince! The num lock button (above the 7 on the number pad) will toggle num lock on and off. When you press it, a notification towards the center of your computer screen should briefly pop up to indicate whether pressing it has turned it on or off. When it says "num lock on" that will mean that the number pad can be used to input numbers, and when it says "num lock off" that means you can use the other inputs listed on some of the keys (ie pg up / pg dn / home / etc). Hope this helps!