What exactly is a leap year? Is it a year we leap for joy?
You might want to leap if an extra day you would enjoy.
You see, our present calendar would be out of sync
If we went along as usual, the great timekeepers think.
In a common calendar, 365 days make a year,
But if it always stayed the same it would soon be off, we fear.
Every four years it happens, and a leap year rolls around.
We have to add an extra day. In February, it is found.
The extra day is added to the calendar worldwide
To any year whose numbers by four will evenly divide.
Except, of course, the century marks that end in double zeros.
Those must be evenly divided by four hundred. That's how the rule goes.