### How many months in a year have exactly 31 days?

7

Step by Step Explanation:
1. We have been asked to find the number of months in a year which have 31 days.
2. Following months in a year have 31 days:
January :  31 days
March   :  31 days
May     :  31 days
July    :  31 days
August  :  31 days
October :  31 days
December:  31 days

Total number of months with 31 days are 7.
3. Hence, there are 7 months in a year with 31 days.