Numbers 3:44-47 NIV

[44] The LORD also said to Moses, [45] “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. [46] To redeem the 273 firstborn Israelites who exceed the number of the Levites, [47] collect five shekels for each one, according to the sanctuary shekel, which weighs twenty gerahs.