Thank you for the help.
No, it's not homework (I'm too old for that) lol. I'm making an air purifier that uses a micro fan to pull the air in a closet through a mesh with activated carbon on top of it. Since there isn't any power in the closet, I decided to use batteries instead...
I'm a beginner and need some help, here's the question, if I connect a 9v energizer alkaline battery to a 12v micro fan rated at .25 Amps, how long (in theory) will the fan run? I believe the battery is rated at app. 595 mAh. If you can solve this please tell me how you did it. Thank you.