Knock Knock. Who's there? 42.

Knock Knock @ HEAD media design from Khalil Klouche on Vimeo.

I love it when somebody takes a concept as simple as a calculator and rethinks it.  Rather than considering it something that manipulates numeric symbols, this box turns math into a haptic/audio experience.  I can imagine some kids finding this much more engaging than manipulating symbols on a display.  For example, I bet kids who are dyslexic would find this more interesting than a regular calculator.  Check out the video.
It looks like a great maker project to me.  Now, how do you figure out where the user is knocking?