Febuary
December has 31 days in the Gregorian calendar, as that is the calendar that we now use.
Not in the Gregorian calendar.
The shortest "month" of the Gregorian calendar has 28 days.
No months in the Gregorian calendar have 80 days.
The eighth month of a year of the Gregorian calendar, August, has 31 days.
April has 30 days in the modern Gregorian calendar.
July is the seventh month of the year in the Gregorian Calendar and one of seven Gregorian months with the length of 31 days.
In the Gregorian calendar, each month does not - so the question is misguided.
June has 30 days. It is the sixth month of the year in the Gregorian calendar.
The month in which the Gregorian Calendar was adopted, because when it was proposed in 1582, there was a difference of 10 days between it and the earlier Julian calendar, and that difference had grown to 13 days by the time that the last countries adhering to the Julian Calendar (Greece and Russia) switched over to the Gregorian Calendar. Because of the "loss" of between 10 and 13 days, the month in which a particular country adopted the Gregorian Calendar might not have had a full moon.
The Gregorian Calendar is an almost identical improvement on the Julian Calendar. The names of the months and the number of days per month are the same. The only difference is that the Gregorian Calendar has three fewer leap year days out of every 400 years. The Julian Calendar averages 365.25 days per year, and the Gregorian Calendar averages 365.2425 days per year. It doesn't seem like much, but after using the Julian calendar for 1 1/2 millennia the accumulated error totaled about 10 days.
yesAnswer:The Julian Calendar was 11 days behind the Gregorian Calendar when Britain and its colonies (including the American colonies) finally switched to the Gregorian Calendar in 1752. The difference increases by three days every four centuries. The Julian Calendar is now 13 days behind, and beginning on March 14, 2100 the difference will be 14 days.