We look at the division of 21158 by 9 
We're looking to find how many times 9 goes into 21158.

Going ahead to step 1:
The number 9 fits into 2 0 times, leaving a remainder of 2.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 2, we get 2.
Take the next digit (1) from the dividend and append it to 2, then repeat: 21 / 9

Let's proceed to step 2:
9 goes into 21 2 times with a remainder of 3.
Use 2 as the next digit of our solution. 
Result so far: 2.0
Deduct 18 from 21 and we're left with 3.
Fetch the next digit (1) from the dividend, attach it to 3 and continue: 31 / 9

Let's proceed to step 3:
9 can be fit into 31 3 times, resulting in a remainder of 4.
Put 3 as the next digit of the answer. 
Result so far: 23.0
If we take 27 away from 31, we end up with 4.
Take the next digit (5) from the dividend and append it to 4, then repeat: 45 / 9

Advancing to step 4:
When dividing 45 by 9, we get 5 with a remainder of 0.
Record the quotient 5 as the next digit in the result. 
Result so far: 235.0
If we take 45 away from 45, we end up with 0.
Fetch the next digit (8) from the dividend, attach it to 0 and continue: 8 / 9

Moving on to step 5:
The number 9 fits into 8 0 times, leaving a remainder of 8.
The next digit of our result is 0. 
Result so far: 2350.0
If we subtract 0 from 8, we get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Going ahead to step 6:
If we divide 80 by 9, we get 8 and a remainder of 8.
Put 8 as the next digit of the answer. 
Result so far: 2350.8
Deduct 72 from 80 and we're left with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Step 7:
If we divide 80 by 9, we get 8 and a remainder of 8.
The next digit of our result is 8. 
Result so far: 2350.88
If we take 72 away from 80, we end up with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

The final outcome is 2350.88, with a leftover of 0.008.