Numbers 3:44-47

3:44 Then the Lord spoke to Moses: 3:45 “Take the Levites instead of all the firstborn males among the Israelites, and the livestock of the Levites instead of their livestock. And the Levites will be mine. I am the Lord. 3:46 And for the redemption of the 273 firstborn males of the Israelites who exceed the number of the Levites, 3:47 collect five shekels for each one individually; you are to collect this amount in the currency of the sanctuary shekel (this shekel is twenty gerahs).