The invention of the first calculating machine is attributed to Pascal, who, in 1642, devised an adding machine to assist his father in the auditing of the government accounts at Rouen. The instrument was able to handle numbers not exceeding six digits. It contained a sequence of engaging dials, each marked from 0 to 9, so designed that when one dial of the sequence turned from 9 to 0 the preceding dial of the sequence automatically turned one unit.