Numbers 3:40-51
                                                                The Substitution for the Firstborn
3:40 Then the Lord said to Moses, “Number all the firstborn males of the Israelites from a month old and upward, and take the number of their names.
                                                                                3:41 And take the Levites for me – I am the Lord – instead of all the firstborn males among the Israelites, and the livestock of the Levites instead of all the firstborn of the livestock of the Israelites.”
                                                                                3:42 So Moses numbered all the firstborn males among the Israelites, as the Lord had commanded him.
                                                                                3:43 And all the firstborn males, by the number of the names from a month old and upward, totaled 22,273.
                                                                                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).
                                                                                3:48 And give the money for the redemption of the excess number of them to Aaron and his sons.”
                                                                                3:49 So Moses took the redemption money from those who were in excess of those redeemed by the Levites.
                                                                                3:50 From the firstborn males of the Israelites he collected the money, 1,365 shekels, according to the sanctuary shekel.
                                                                                3:51 Moses gave the redemption money to Aaron and his sons, according to the word of the Lord, as the Lord had commanded Moses.