72121 ÷ 9 = 8013 R4
Let's divide 72121 by 9.

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 (1) of the dividend behind the 0 and repeat the process: 1 / 9

Step 3:
9 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of of the result. 
Result so far: 80
Subtract 0 from 1 to get 1.
Bring next digit (2) of the dividend behind the 1 and repeat the process: 12 / 9

Step 4:
9 goes into 12 1 times with a remainder of 3.
Write down 1 as next digit of of the result. 
Result so far: 801
Subtract 9 from 12 to get 3.
Bring next digit (1) of the dividend behind the 3 and repeat the process: 31 / 9

Step 5:
9 goes into 31 3 times with a remainder of 4.
Write down 3 as next digit of of the result. 
Result so far: 8013
Subtract 27 from 31 to get 4.

The final result is 8013 with a remainder of 4.