$4.6 Trillion to rebuild every building in the United States and to completely replace the airline industry with high speed rail???? Hmmm....
Yeah - I calculated it to cost $4.7 trillion.
I had a prof that said if a number had too many significant figures than seemed reasonable, the number was just pulled from their butt. For a number to replace every building, I’m guessing that it might be some number, with a +/- of $50 trillion dollars.