1,297. Intentionally Inexact

Hilchos Kiddush HaChodesh 11:6

Pursuant to the previous halacha, if someone should happen to ascertain that one of the Rambam’s methods leads to a small defect in calculation, this is intentional. That’s because this procedure has another advantage: it will yield correct results through approximate calculations without resorting to complicated math. Therefore, one who is not an expert in such things need not be bothered with complex calculations that will make no difference in determining when the moon will appear.

Hilchos Kiddush HaChodesh 11:7

Certain basic principles must be understood before undertaking astronomical calculations, whether to determine the visibility of the moon or for other things. The “ sphere” (i.e., the area visible around the Earth) is divided into 360 degrees. There are 12 constellations of 30 degrees each, beginning with Aries. Each degree is divided into 60 minutes, and each minute into 60 seconds. Seconds can be further divided into 60 parts, and so on, further subdividing as far as one likes.