Android - Calculator help / source wanted

I know Android is open source, but are all the apps that they make open source?

Is there a way I can get my hands on the Android Calculator source?

Otherwise, can someone point me in the direct开发者_开发百科ion to an open source calculator, or a tutorial to make one?

Thanks!

Android calculator source is browseable here: Calculator source tree

i create an open source calculator its good for beginner android learner. download link below : http://sourceforge.net/projects/androidcalculat/