'Fifteenth' in the Bible

The Festival of Unleavened Bread to the Lord is on the fifteenth day of the same month. For seven days you must eat unleavened bread.

“Tell the Israelites: The Festival of Booths to the Lord begins on the fifteenth day of this seventh month and continues for seven days.

“You are to celebrate the Lord’s festival on the fifteenth day of the seventh month for seven days after you have gathered the produce of the land. There will be complete rest on the first day and complete rest on the eighth day.