21239 ÷ 9 = 2359 R8
Alright, let's work through the division of 21239 by 9 step by step.

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

Step 2:
9 goes into 21 2 times with a remainder of 3.
Write down 2 as next digit of of the result. 
Result so far: 2
Subtract 18 from 21 to get 3.
Bring next digit (2) of the dividend behind the 3 and repeat the process: 32 / 9

Step 3:
9 goes into 32 3 times with a remainder of 5.
Write down 3 as next digit of of the result. 
Result so far: 23
Subtract 27 from 32 to get 5.
Bring next digit (3) of the dividend behind the 5 and repeat the process: 53 / 9

Step 4:
9 goes into 53 5 times with a remainder of 8.
Write down 5 as next digit of of the result. 
Result so far: 235
Subtract 45 from 53 to get 8.
Bring next digit (9) of the dividend behind the 8 and repeat the process: 89 / 9

Step 5:
9 goes into 89 9 times with a remainder of 8.
Write down 9 as next digit of of the result. 
Result so far: 2359
Subtract 81 from 89 to get 8.

The final result is 2359 with a remainder of 8.