A good way to know whether a month has 31 days is by counting the knuckles and gaps between knuckles. "Landing" on a knuckle means that month is 31 days. So, P

A good way to know whether a month has 31 days is by counting the knuckles and gaps between knuckles. "Landing" on a knuckle means that month is 31 days. So, Pointer finger knuckle = January = 31 days Between pointer/middle = Feb != 31 days Middle finger knuckle = March = 31 days And so on, just looping back to the first knuckle when you get past the pinky knuckle.