What are the tricks to remember how many days in every month?

The rhyme goes:

Thirty days hath September, April, June, and November;

All the rest have thirty-one, excepting February alone,

And that has twenty-eight days clear, and twenty-nine in each leap year.

You can also tab each of your knuckles and the wells in between, while reciting the months of the year. Start with the first knuckle and work your way to the knuckle on your baby finger. When you get to the last knuckle, tap twice and go back to the first knuckle. Your knuckles, which are higher up than the wells in between, represent the months with 31 days: January, March, May, July, August, October, December. The wells in between your knuckles represent the months with 30 days: April, June, September, November. February is the exception with 28 days and 29 in a leap year.