The Six Factor Formula or Neutron Lifecycle, is used in nuclear engineering to describe all the possible events in the life of a neutron and effectively describes the state of a finite multiplying system. The reactor is critical when exactly every fission initiates another fission. 

I remember the mnemonic very well, hard to forget. I can't imagine they teach that in today's more politically correct Navy.  I also remember that I only missed 1 question on the RP final, so I must have not only remembered the mnemonic, but how to use it right?

Brush up on your reactor principals on Google over your favorite beverage in your six factor formula coffee mug, steel pint glass or stainless steel tumbler while wearing your six factor formula or It Gets Better After Orse socks.