'Fifteenth' in the Bible

Then on the fifteenth day of the same month there is the Feast of Unleavened Bread to the Lord; for seven days you shall eat unleavened bread.

“Speak to the sons of Israel, saying, ‘On the fifteenth of this seventh month is the Feast of Booths for seven days to the Lord.

‘On exactly the fifteenth day of the seventh month, when you have gathered in the crops of the land, you shall celebrate the feast of the Lord for seven days, with a rest on the first day and a rest on the eighth day.