I needed to look up the syntax for Excel’s DATEDIF function this afternoon. For some weird reason, none of the help files and wizards in Excel mention this very useful function. I’ve used it before, numerous time, and I knew it was in there, quietly waiting, but I just couldn’t remember what arguments went where in the formula. Luckily documentation exists out there on the web, particularly Chip Pearson’s page on the DATEDIF Function. I really enjoy his prefacing paragraph about Excel’s reticence over the DATEDIF function:
The DATEDIF function is a worksheet function that computes the difference between two dates. This function is available in all versions of Excel since version 5, but is documented only in the help files for Excel 2000. It isn’t documented in either Excel 97 or Excel 2002. DATEDIF has, for whatever reason, been treated as one of the drunk cousins of the Function Family. Excel knows he lives a happy and useful existence, and will acknowledge his existence when you ask, but will never mention him in “polite” conversation.