The answer to which is now known to be 42.
4 seconds sound clip from The Hitchhiker's Guide to the Galaxy (1981) - Episode 6 sitcom.
You can hear this line at 00:01:55.952 in the Blu-ray version of the TV Series.
Quote context
[...]
- Why not?
- Shut up.
- Excitement and adventure and really wild things...
- Excitement and adventure and really wild things have been dogging Arthur Dent now for some days.
- He has, for instance, had his planet demolished to make way for a new hyperspace bypass...
- The answer to which is now known to be 42.
- Can they now relax for a while and take stock? No.
- The ship does in fact belong to Disaster Area.
- Of this, however, Arthur Dent and his companions are totally unaware.
[...]