The Pascaline was a mechanical adding machine, or rather a family of such machines, designed by Blaise Pascal (1623-1662). Only one true mechanical calculator, called Schickard's calculating clock, had been created before Pascal invented the Pascaline, and Pascal almost certainly never saw Schickard's device or even heard how it worked. Thus Pascal and Schickard must both be credited with independent invention of the "first" true calculator. However, Pascal has the distinction that a large number--about 50--of his adding machines were actually produced and used.

Pascal's father was a tax collector, and put his son to work adding columns of tax figures. The tedium of this job moved Pascal to conceive the basic design of his adding machine when he was 19 years old. By today's standards the Pascaline was crude: a shoebox-size device that could add base-10 (ordinary decimal) numbers anywhere from 6 to 8 digits long, depending on the individual...