Gotfreid Leibniz

 

1646-1716. Leibniz designed a "Stepped Reckoner", which was constructed by a man named Olivier, of Paris. It used a movable carriage so that it could multiply, with operands of up to 5 and 12 digits and a product of up to 16. The user had to turn a crank once for each unit in each digit in the multiplier; a fluted drum translated the turns into additions.

But the carry mechanism required user intervention, and didn't work in all cases.Leibniz's machine didn't get forgotten, but it did get misplaced in an attic within a few years and stayed there until 1879 when a man working on the leaky roof noticed it. Leibniz, or Leibniz, is also the co-inventor, along with Newton, of  the calculus.