People tend to think of the computer as a development of the twentieth century, but predecessors can be traced far back into history. As early as 450 B.C. the abacus was used for computations, and other early devices for keeping up with numbers include the Aztec calendar. The first mechanical calculator, used for addition, subtraction, multiplication, and division, was developed by a German mathematician named Wilhelm Schikard in the early seventeenth century. Soon after, in 1642, Frenchman Blaise Pascal built an adding and subtracting machine. His accomplishment was honored in the naming of Pascal, a modern computer language.