Today, we take digital consumer electronics so for granted we often forget that just two generations something as simple as a calculator was a marvel of engineering and technology. 

Actually, before electricity, mechanical calculator machines had been around for centuries. But only Curt Herzstark was able to successfully make a fully operational, portable mechanical calculator, which was named the Curta

Alex Bellos of number obsessed  showcases the amazing piece of engineering in this video that has amassed over 50,000 views since the weekend.