By 1887, he had built eight machines and decided to try to sell them. He encountered several problems. It was as much a struggle to get the machines on the market as it was to invent them. Also, he would have to train the operators. (Such training, incidentally, turned into a highly profitable sideline in later years.) According to Felt, college professors as a rule ignored this step forward into mechanical mathematics, and bookkeepers seemed to think that it was an interference with their chosen vocation.

However, in a few years the Comptometer, advertised as "The Machine Gun of the Office," and the Burroughs keydriven adding and listing machines became the most popular accounting machines.