Gottfried Wilhelm Leibniz (1646 – 1716) was a German polymath and one of the most important logicians, mathematicians and philosophers of the Enlightenment era. He famously developed calculus independently from Isaac Newton.
He also invented the Stepped Reckoner (or Staffelwalze), a mechanical calculator that improved upon the Pascaline by being capable of all four basic arithmetic operations. He’s also considered the first to realise the utility of the binary number system, the foundation of all modern digital computers. He documented and refined it extensively in his lifetime.