Pope Fact #2 - Papal names
Popes often change their names when they take the oath of office and officially begin their Popedum. The choice of a papal moniker is often a means of symbolically thanking and honoring a past pope. The spanking-new Pope just takes the name of a prior pope and adds a Roman Numeral. One need not look further than our current Pope, John Paul II (JP to his friends) to see this phenomenon in action.
As a result of this practice, some papal names go into the double digit, such as John, Stephen, Barcelona, Dr Dre, and Gregory.
On a personal note, I would just like to thank the 37 popes that have come around since Pope Sixtus V's death in 1590 for showing the self-restraint and maturity not to take the name Sixtus the Sixth.