In Bemidmar 3, if we count the numbers of 3 Levite clans (Gershom – 7 500, Kohath – 8 600 and Merari – 6 200) we come up with a number – 22 300. However in Bemidbar 3:39 it is said that “All the Levites numbered by Moses and Aaron at the order of the Lord, all the males of one month old and over numbered in the order of their families, were twenty-two thousand”.
Is there any halachic explanation for this discrepancy?
You are asking an excellent question. The gemorah (Bechoros 5a, also see Rashi Bamidbar 3-39) asks your question and tells us that the reason for the discrepancy is because in verse 39 we are only mentioning those Leviim that needed to be redeemed. The other 300 were bechorim themselves, and a bechor did not have to redeem himself because he does it himself, and it is automatic.