Peter W. Shor took Deutsch’s black box to the next logical level. Quantum computers are very good at giving a property of all answers. By a bit of mathematical trickery Shor changed the problem of factoring numbers into finding a property of all solutions of a related problem. In specific it looks for the period of all solutions. Quantum weirdness is then used to massage the personalities so that the correct answer comes out. As in all “real world” quantum algorithms they will give the correct answer only with a certain probability. No quantum algorithm will guarantee the correct answer and the running time increases as the chance of error decreases.