Numbers 3-4

The census continues. This time, the Levite males older than 1 month are counted as well the number of the firstborn sons of all of Israel.

Here, we see somewhat a parallel from the childbirth purity laws. Remember how women were unclean for the first 40 days if it was a boy, but 80 days if it's girl? (what if she has twins, a son and daughter a once!) It still is a weird rule, but at least it roughly parallels the male census count as only boys 1 month or older are counted.

God plans to "redeem" the firstborn Israelite boys that God reserved in lieu of killing them at Passover and switch the reservation to the Levites. The census count shows they are the same number, except off by 273. The difference will be made up financially.

The Levites are organized by clan from the original sons of Levi. They will have specific priestly duties based on their family clan.

The Kohathite men aged 35 or older (2750) responsible for moving the sacred objects of the tabernacle when the camp moved. This process is supervised by Aaron or his sons, lest the Kohathite priests die.

The Gershonite men aged 35 or older (2630) carry the Tabernacle curtains. The Merarite men 35 and older (3200) carry the frame poles. Both of these are supervised by one of Aaron's sons.