Daily Aliya for Bamidbar, Shishi (6th Aliya)
Aliya Summary: G‑d then tells Moshe to count all the firstborn Israelites — because the holiness of each Israelite firstborn was now to be “transferred” to a Levite. The census revealed that there were 273 more firstborn than Levites. Each of these “extra” firstborns (as determined by a lottery) gave five shekel to the priests, and was thus “redeemed.”
A mass “redemption of the firstborns” is conducted by an exchange of 22,000 Leviyim (non- b’chorim) for 22,000 b’chorim (non- Leviyim) and a payment of five silver sheqels each for the remaining 273 firstborns to Aharon and his sons.
Imagine gathering 22,273 people and asking each to choose a card from a batch of 22,273 cards, 22,000 of which have the words BEN LEVI on them and 273 have the words 5 shekel on them. This, says Rashi, is how they determined who would pay the 5 shekels for the exchange.