Numbers 3:44-47

44Then the Lord spoke to Moses, saying,

45“1Take the Levites instead of all the firstborn among the sons of Israel and the cattle of the Levites. And the Levites shall be Mine; I am the Lord.

462For the ransom of the 273 of the firstborn of the sons of Israel who are in excess beyond the Levites,

47you shall take 3five shekels apiece, per head; you shall take them in 4terms of the shekel of the sanctuary (5the shekel is twenty 6gerahs),