#NoCalculator : Equation of time.
Was searching for an approximate way to figure out the "equation of time" quickly in your head, w/o any calculator. Found this interesting poem on the web :
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.
The mid of month four, add no more
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.
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I still figure out whether this month ends in 30 or 31 using the poem's first line
30 days has September,
April, June and November.
Your month didn't get caught in the above line? Then it's 31 days.