Major innovations made from the establishment of abacus to the present 5th computer generation

He invented a calculating machine known as Leibniz's Wheel or the Step Reckoner. It could add and subtract, like Pascal's machine, but it could also multiply and divide. It did this by repeated additions or subtractions, the way mechanical adding machines of the mid to late 20th century did.

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answer; i believe that the correct answer is (calculated field);

answer; its the top layer;