who devised the calculator known as the step reckoner
Stepped reckoner The step reckoner (or stepped reckoner) was a digital mechanical calculator invented by the German mathematician Gottfried Wilhelm Leibniz around 1672 and completed in 1694.[1] The name comes from the translation of the German term for its operating mechanism, Staffelwalze, meaning 'stepped drum'. It was the first calculator that could perform all four arithmetic operations.[2]
Pascal's calculator Pascal designed the machine in 1642,[3] and after 50 prototypes, he presented it to the public in 1645, dedicating it to Pierre Séguier, then chancellor of France.[4] Pascal built around twenty more machines during the next decade, many of which improved on his original design. In 1649, King Louis XIV of France gave Pascal a royal privilege (similar to a patent), which gave him the exclusive right to design and manufacture calculating machines in France. Nine Pascal calculators presently exist;[5] most are on display in European museums.