Which is correct?
- "...during the entire hour and twelve minute lecture."
or
- "...during the entire hour-and-twelve minute lecture."
Which is correct?
or
Hour-and-twelve-minute is an adjectival phrase describing 'lecture'.
It is simpler for a reader to see this if the words are hyphenated.
"...during the entire hour and twelve minutes lecture.", is the better one,
The dash is a handy device, informal and essentially playful, telling you that you're about to take off on a different tack but still in some way connected with the present course — only you have to remember that the dash is there, and either put a second dash at the end of the notion to let the reader know that he's back on course, or else end the sentence, as here, with a period. __ Lewis Thomas