How to make "the end date of the month" in diary

[Kiwon Um]

Dear emacs users:

The diary-float function has a powerful date calculation ability.
Then,
how can I calculate "the end date of the month"?

For monthly scheduled tasks, I want to note all end dates of all
months:
1/31, 2/28, 3/31, and so on,

i.e. in org-mode,
* A monthly task
 SCHEDULED: <%%(diary-...)>

Thanks.

--
Kiwon Um