Am I giving him too much credit in thinking that he does know — rounding within, say, a trillion dollars — and is simply playing dumb to deflect an “unhelpful” question, or have we reached the point where we’re hemorrhaging money so quickly that even the president can’t keep count? C’mon. The Five Trillion Dollar Man knows.

Here’s a better question: Why did Letterman broach this subject? Partisan that he is, there were a million things he could have asked O to make life easier for him (“Tell us the story about killing Osama Bin Laden again, papa”) and yet he asked him about one of his biggest political liabilities. I’m thinking the White House must have requested the question because this was their big chance to speak directly to casual voters in rebutting one of the GOP’s strongest attacks, and that Dave somehow wandered off-script by trying to pin Obama down on the number. Or it could be that, in his own odd way, he was trying to help O out by purposely floating a much lower figure on the debt ($10 trillion) for the benefit of semi-comatose low-information voters. The problem with that, though, is that “$10 trillion” is likely as startling a figure to an LIV as “$16 trillion” given that they have no mental benchmarks on federal spending over the past decade to reference. Can’t figure out why Dave would bring it up.

No serious talk of entitlement reform here. Of course.