How many months have exactly 30 days?

The correct answer is based on the knowledge of how many days are in each month of the Gregorian calendar, which is the calendar system used by most of the world. In this calendar, there are four months that contain exactly 30 days: April, June, September, and November.

Each of these months follows the convention that they have 31 or 30 days alternating, except for February, which has 28 or 29 days in leap years. Since the question specifically asks for the months with exactly 30 days, the total comes to four distinct months. This understanding of the month structure in the Gregorian calendar allows one to confidently arrive at the number of months with precisely 30 days.