Numbers 9:20

9:20 When the cloud remained over the tabernacle a number of days, they remained camped according to the Lord’s commandment, and according to the Lord’s commandment they would journey.

Numbers 18:16

18:16 And those that must be redeemed you are to redeem when they are a month old, according to your estimation, for five shekels of silver according to the sanctuary shekel (which is twenty gerahs).