Bilangan 1:20

1:20 And they were as follows:

The descendants of Reuben, the firstborn son of Israel: According to the records of their clans and families, all the males twenty years old or older who could serve in the army were listed by name individually.

Bilangan 26:7

26:7 These were the families of the Reubenites; and those numbered of them were 43,730. ¹ 

[26:7]  ¹ sn The Reubenites had decreased from 46,500 to 43,730.