21138 ÷ 9 = 2348 R6
We're going to perform division on 21138 with 9 as the divisor.

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 (1) of the dividend behind the 3 and repeat the process: 31 / 9

Step 3:
9 goes into 31 3 times with a remainder of 4.
Write down 3 as next digit of of the result. 
Result so far: 23
Subtract 27 from 31 to get 4.
Bring next digit (3) of the dividend behind the 4 and repeat the process: 43 / 9

Step 4:
9 goes into 43 4 times with a remainder of 7.
Write down 4 as next digit of of the result. 
Result so far: 234
Subtract 36 from 43 to get 7.
Bring next digit (8) of the dividend behind the 7 and repeat the process: 78 / 9

Step 5:
9 goes into 78 8 times with a remainder of 6.
Write down 8 as next digit of of the result. 
Result so far: 2348
Subtract 72 from 78 to get 6.

The final result is 2348 with a remainder of 6.