All you need to do is,
1. Click "Camera" icon in the app & take the picture (or) choose the existing the picture from gallery.
2. Click "Detect"
3. That's it, the in-build "Age Detector" will start scan your pic and determines your age.
4. Just share your app determined age with fiends via Facebook, Twitter, Instagram & Whatsapp.
Note: The app requires internet connection.
So, what are you waiting for?. Download "How Old Are You? - Prank" app, detect your age & share this funny prank app with your friends.