'Fifteenth' in the Bible

Then on the fifteenth day of the same month will be the festival of unleavened bread to the Lord; seven days you must eat unleavened bread.

"Tell the Israelites, 'On the fifteenth day of this seventh month is the Festival of Temporary Shelters for seven days to the Lord.

"'On the fifteenth day of the seventh month, when you gather in the produce of the land, you must celebrate a pilgrim festival of the Lord for seven days. On the first day is a complete rest and on the eighth day is complete rest.