민수기 3:49의 주석

העדפים על פדויי הלוים THE OVERPLUS THAT WERE MORE THAN THOSE REDEEMED BY THE LEVITES means, that were more than those whom the Levites redeemed by their own person.

הפדיום. The final letter ם here is superfluous just as it is superfluous in the word ריקם instead of simply ריק. (Genesis 31,42), or the same letter in the word הכנם in Exodus 8,13, or in the word שלשום in Genesis 31,2. Our sages explain that there were a total of 300 Levites in excess of the number of firstborn that they were to redeem (replace). (Bechorot 5, compare Rashi on verse 39). The reason that the verse described these as “leftover,” “in excess,” is that a firstborn cannot redeem another firstborn, i.e. there must have been a number of firstborn Levites also.