Commentary for Numbers 3:46

ואת פדויי השלשה וגו׳ AND AS FOR THOSE THAT ARE TO BE REDEEMED [OF THE TWO HUNDRED THREESCORE AND THIRTEEN etc.]… [THOU SHALT TAKE…] — This means, “and as for those firstborn who are yet to be redeemed among them (the Israelites), viz., the 273 who were in excess among them, being more than the 22,000 Levites, of them thou shalt take חמשת שקלים לגלגלת FIVE SHEKELS BY THE POLL, such, viz., twenty pieces of silver, was the selling price of Joseph who was Rachel’s firstborn. (Jerusalem Talmud Shekalim 2:4; Genesis Rabbah 84:18).

Take five shekolim. In order that you do not err and say that “the פדויי (redemption) of the 273…” is to be explained like “those whose numbers were in excess of those פדויי (redeemed) through the Levites” (v. 49). There Rashi explains that [the word פדויי] refers to “those redeemed by the very presence of the Levites.” Thus you might think that you should also take five shekolim from them. Therefore, Rashi explained that “the redemption of the 273…” refers to the firstborn who required redemption, because they did not have anyone to redeem them and from them you should “take five shekolim from each individual.”