72021 ÷ 9 = 8002 R3
Alright, let's work through the division of 72021 by 9 step by step.

Step 1:
9 goes into 7 0 times with a remainder of 7.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 7 to get 7.
Bring next digit (2) of the dividend behind the 7 and repeat the process: 72 / 9

Step 2:
9 goes into 72 8 times with a remainder of 0.
Write down 8 as next digit of of the result. 
Result so far: 8
Subtract 72 from 72 to get 0.
Bring next digit (0) of the dividend behind the 0 and repeat the process: 0 / 9

Step 3:
9 goes into 0 0 times with a remainder of 0.
Write down 0 as next digit of of the result. 
Result so far: 80
Subtract 0 from 0 to get 0.
Bring next digit (2) of the dividend behind the 0 and repeat the process: 2 / 9

Step 4:
9 goes into 2 0 times with a remainder of 2.
Write down 0 as next digit of of the result. 
Result so far: 800
Subtract 0 from 2 to get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 9

Step 5:
9 goes into 21 2 times with a remainder of 3.
Write down 2 as next digit of of the result. 
Result so far: 8002
Subtract 18 from 21 to get 3.

The final result is 8002 with a remainder of 3.