Good afternoon Rick and readers. I thought I had posted additional comment this morning but now I figure I must have done something incorrectly because it seems not to be there. I now stand convinced of the mathematical soundness to switching. It would be interesting to see a simulation of the situation where there are five doors at the outset and Monty will reveal one "losing" door after each iteration of choices made by the contestant. What choice should the contestant make after each iteration - stick or switch? Thanks again Rick for the enlightenment. Keep up the great work.