Numbers 4:1
The Lord spoke to Moses and Aaron. He said:
The firstborn of the Israelites received one thousand three hundred and sixty-five pieces of silver according to the Sanctuary standard.
Moses received the 1,365 pieces of silver as ransom from those who were left when the Levites had redeemed the rest.
So for each one, you are to pay five pieces of silver, according to the official standard,
But you have to buy back the 273 of the firstborn of the sons of Israel who outnumber the Levites.
“Take the Levites instead of all the firstborn of Israel’s sons, and the cattle of the Levites instead of their cattle; the Levites shall be my own.