[Oh, Don.

When Robert doesn't get an answer, his expression softens a little, and he reaches out to take Don's hand.]

... M-May I ask you... something else, then?

Could you... finish this mathematical problem for me...? [He presents the paper to Don, with an obvious air of nervous hope.]

I... want to see... [... it's terrible, but he doesn't know a nicer way to say it...] ... whether your intellect is i-intact.