Display number of days in different months.

Dear All. 

I have a timesheet.

When I entered the number: 1-12 as a month in a year, the table displayed the number of days in this month. But the issue is the days in a month are different so each time I will get the 28days, 30 days, or 31 days. If my table is fixed with rows, for example, 31 rows for the biggest days in a month, when I did the timesheet in Feb, I had to delete 3 days in my table. 

I want to display an exact number of days corresponding with the different entered months.

Do I able to do it?