Thirty days hath September, April, June, and November; all the rest have thirty-one. Excepting February alone, which hath but twenty-eight, in fine. Till leap year gives it twenty-nine.

Explanation

This is one of the most widely known rhymes in the English language: it settles the question of how many days are in each month in seconds, leap-year exception included.

Alternative mnemonics

• Thirty days in September, April, June, and November. All the rest have 31, except for February, which has 28, but Leap Year gives it 29.