OffOf - Percentage Calculator

My wife texted me a week ago while shopping with and for the kids asking: "What is 70% off of $39?" After I answered i realized it be great if she could be able to quickly get the answer with an app. I also had been really wanting to learn Cocoa for a long while and had recently decided to do it as soon as I had a reason. So here was my reason :)
I stayed up all night that night and finished it in the morning. Was fun!
6 Days later Apple approved it and its now free in the app store!
https://itunes.apple.com/us/app/lumo.me/id883081837

As you can see i spent a ton of time on the website ;) http://offof.drewwilson.com

Go grab it for yourself!

I'll be re-writing it in Swift next!