We have been given to find out which number comes 1000 before 30,638. We can say it as which number is 1000 less than 30,638.
To answer this question we will subtract 1000 from 30,638.
30,638-1000
After subtracting 1000 from 30,638 we will get 29,638. Therefore, 29,638 is 1000 less than 30,638.