Between two census took 40 years

Numbers 26:1-65
After the plague the Lord said to Moses and Eleazat son of Aaron, the priest, "Take a census of the whole Israelite community by families - all those twenty years old or more who are able to serve in the army of Israel."
Reuben less 2700 men
Simeon less 37000 men.
Other tribes are not changed too much.
Not one of them was among those counted by Moses and Arron the priest when they counted the Israelites in the Desert of Sinai. For the Lord had told those Israelites they would surely die in the desert, and not one of them was left except Caleb son of Jephunneh and Joshua son of Nun.
The numbers are slightly fewer than in the first census (one whole generation has been replaced by another). The reason for the census, this time, was so that the land could be shared out fairly according to the size of the different groups.
Why?
God's word has been done for Israelites did not listened to God's word, then they will know that God is the Lord.
Second census is prepare for the coming war and the land could be shared out fairly.
Number of Reuben and Simeon was less more for they were dead for the plague etc.
Two census between Sinai and Shittim, their were replaced by another generation. It passed 40 years in desert.
How?
Do not waste the time in desert, be humble and knowing the Lord is my way,  hurry to get blessing from the Lord.