[TomGuy]

31 + 7 + 13 = 51 which is larger than 47.

The problem with that calculation is that many of Paul's supporters would go Libertarian or similar, if Paul dropped out. They would not necessarily go to Santorum or Gingrich.

[plain talk]

Yes - some of them would, you are correct. But not all - many conservatives support Paul as well. The biggest part of the equation is the addition of Newt and Santorum numbers which tells the story right there.