Amazing Old Calculator (Curta)

Alex's book: http://amzn.to/1l0yX46

The Curta is a pocket-sized, mechanical, digital calculator!!! It was invented by Curt Herzstark.

Shown here by Alex Bellos, author of Alex's Adventures in Numberland.

More about our contributors, including Alex, at http://www.numberphile.com/team/index.html