Wasn't it 6 x 9.

42 in base 13.

Then again...

http://groups.google.com/group/alt.fan.douglas-adams/msg/d1064f7b27808692



>As I remember it it does not equal 42 like 6X7 does. I thought it was 7X9 but it may 7X8 or some other multiplication, but it definitely does not equal 42, which was the joke of it.
>
>
>>Or maybe 'What is 6 x 7?' :o)
>>
>>
>>>>And the answer to 42 was ?
>>>>
>>>>>42
>>>
>>>What is 7 X 9?