I know Feb is 28 (or 29), I know Oct is 31 because of halloween, and I know July is 31 because of a friend's b-day.. but other than that, no idea which ones have 30 or 31 without looking at a calendar.
use the knuckles method. hold out your hands, palm down. make fists. look at the top of your knuckles. look at the knuckles and the spaces in between the knuckles. start counting the months from the left, with a month for each knuckle and space. the knuckles represent long months (31) and the spaces represent short months (30 or less). you will see they alternate until you reach the last knuckle (july), then you have to jump to your other hand and that's another knuckle (august) and keep going from there until you run out of months (december)