In terms of numerical assertions, Wednesday’s presidential debate at times seemed like a playground fight instead of a substantive encounter. President Obama and GOP nominee Mitt Romney threw figures at each other as if they were snowballs.

“You’ve got a $5 trillion tax cut!”

“Do not! You’re the one with a $716 billion Medicare cut!”

“Not true!”

"Yes true!”

And so on. Eventually the school bell rang and they had to go in. Or moderator Jim Lehrer said it was over and they shook hands. One or the other.

That can’t be edifying for viewers who don’t keep Congressional Budget Office reports on their bedside tables. So we’ll try to explain in a basic way the facts as we understand them behind some of the candidates' primary substantive disagreements.