Today's AWAD is:

nonplus (non-PLUS, NON-plus) verb tr.
To put at a loss for what to do, think, or say; perplex.

noun
A state of perplexity or bewilderment.

[From Latin non plus (no more).]

If it doesn't add up, you're nonplussed. And there's not much you can do about it.

And there's not much else I can say about it.