21 August 1888: Burroughs patents his adding machine

William Seward Burroughs received a US patent for his adding machine, one of the first commercially successful calculators. Bank clerks who spent long hours adding columns by hand were ideal customers. His company grew into the Burroughs Corporation, a major office-equipment and later computer maker, which eventually merged with Sperry to form Unisys. Automating boring, error-prone work has been a profitable business for a very long time.

The lesson: Tools that automate tedious, costly work tend to find customers, from adding machines to modern software.