Another famous two train puzzle by Sam Loyd is shown below. For the bumblebee problem, the time at which the bumblebee reaches the second train can be calculated as 60 t = 100 - 10 t. Further calculations give an infinite series. When mathematician John von Neumann first heard the problem, he gave an answer almost immediately. When asked for his technique, he explained his summation of the infinite series. But perhaps a simpler method exists.