Numbers 3:45-48

“Take the Levites in place of all the firstborn of Israel, and the livestock of the Levites in place of their livestock. The Levites are to be mine. I am the LORD. To redeem the 273 firstborn Israelites who exceed the number of the Levites, collect five shekels for each one, according to the sanctuary shekel, which weighs twenty gerahs. Give the money for the redemption of the additional Israelites to Aaron and his sons.”