If I recall correctly, her brain isn't "fresh enough." She left Earth six months before Arthur so her data is "incomplete."

I guess, if that's in the book; been too long since I read it. Not sure that really holds up though, considering it would presumably be genetic and Arthur's genetics hadn't changed since he was born. Neither had Trillian's.

@Knixon said:

I guess, if that's in the book; been too long since I read it. Not sure that really holds up though, considering it would presumably be genetic and Arthur's genetics hadn't changed since he was born. Neither had Trillian's.

While DNA sequence in the genome stays the same as the biological organism ages, there is a continuous process of damage, repair, mutations and recombinations.

The data - memory formed and stored probably via DNA methylation - about Earth at that critical point in time, in Arthur's brain, is more recent (up to date) than that of Trillian.

So, Frankie and Benjy (Lunkwill and Fook) were interested in buying Arthur's brain, because Arthur was on Earth right before it went ka-blooey and his brain may hold the Ultimate Question that the computer was trying to find out.

Actually, Trillian's brain is never mentioned in the book. I forget where I heard she was unacceptable. Trillian was an option in the radio show, but not in any subsequent versions. I suspect Douglas Adams left her out to focus the story back to Arthur.

My overall point about all of this, though, is that apparently the Ultimate Question - even if they had gotten it right - was pointless.

"What do you get if you multiply six by nine?" was obviously pointless.

But the CORRECT question (to get 42), "What do you get if you multiply six by seven?" is also pointless.

The pointlessness is the point.

@Knixon said:

My overall point about all of this, though, is that apparently the Ultimate Question - even if they had gotten it right - was pointless.

"What do you get if you multiply six by nine?" was obviously pointless.

But the CORRECT question (to get 42), "What do you get if you multiply six by seven?" is also pointless.

Frankie: "No, no, too literal, too factual, wouldn’t sustain the punters’ interest."