Thematic Bible: Of the firstborn

And for those 273 who are to be redeemed of the firstborn of the Israelites who outnumber the Levites, You shall take five shekels apiece, reckoning by the sanctuary shekel of twenty gerahs; you shall collect them, And you shall give the ransom silver from the excess number [over the Levites] to be redeemed to Aaron and his sons. read more.
So Moses took the redemption money from those who were left over from the number who were redeemed by the Levites. From the firstborn of the Israelites he took the money, 1,365 shekels, after the shekel of the sanctuary. And Moses gave the money from those who were ransomed to Aaron and his sons, as the Lord commanded Moses.

Everything that first opens the womb in all flesh, which they bring to the Lord, whether it be of men or beasts, shall be yours. Nevertheless the firstborn of man you shall surely redeem, and the firstling of unclean beasts you shall redeem. And those that are to be redeemed of them, from a month old shall you redeem, according to your estimate [of their age], for the fixed price of five shekels in silver, according to the shekel of the sanctuary, which is twenty gerahs.