I've been asked to post a verse I composed on a spreadsheet for constructing
a vertical decliner. Here it is, in a slightly revised version:
On September one, trust the sun.
Come Halloween, subtract sixteen.
On Christmas Day, you're OK.
For your Valentine true, add a dozen and two.
When taxes are due, the dial is true.
At the mid of May, take four away.
On June fourteen, don't add a bean.
When August begins, add seven little mins.
The rest is easy: for any date,
All you do is interpolate.
The line about taxes works for USA. A more universal alternate might run,
The mid of month four, add no more.
