9104 divided by 21 
We're looking to find how many times 21 goes into 9104.

Moving on to step 1:
21 goes into 9 0 times with a remainder of 9.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 9, we get 9.
Include the next digit (1) from the dividend after 9, then repeat: 91 / 21

Advancing to step 2:
When dividing 91 by 21, we get 4 with a remainder of 7.
Put 4 as the next digit of the answer. 
Result so far: 4.0
Deduct 84 from 91 and we're left with 7.
Fetch the next digit (0) from the dividend, attach it to 7 and continue: 70 / 21

Going ahead to step 3:
70 divided by 21 is 3 with a remainder of 7.
Use 3 as the next digit of our solution. 
Result so far: 43.0
Subtract 63 from 70 to get 7.
Bring next digit (4) of the dividend behind the 7 and repeat the process: 74 / 21

Step 4:
If we divide 74 by 21, we get 3 and a remainder of 11.
Use 3 as the next digit of our solution. 
Result so far: 433.0
The remainder is 11 after subtracting 63 from 74.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

On to step 5:
If we divide 110 by 21, we get 5 and a remainder of 5.
The next digit of our result is 5. 
Result so far: 433.5
The remainder is 5 after subtracting 105 from 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Moving on to step 6:
21 can be fit into 50 2 times, resulting in a remainder of 8.
The number 2 becomes the next digit in our result. 
Result so far: 433.52
Subtract 42 from 50 to 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.

On to step 7:
21 can be fit into 80 3 times, resulting in a remainder of 17.
Use 3 as the next digit of our solution. 
Result so far: 433.523
If we take 63 away from 80, we end up with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

On to step 8:
The number 21 fits into 170 8 times, leaving a remainder of 2.
The next digit of our result is 8. 
Result so far: 433.5238
The remainder is 2 after subtracting 168 from 170.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Let's proceed to step 9:
21 can be fit into 20 0 times, resulting in a remainder of 20.
Use 0 as the next digit of our solution. 
Result so far: 433.5238
Subtracting 0 from 20 leaves us with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Moving on to step 10:
The number 21 fits into 200 9 times, leaving a remainder of 11.
Put 9 as the next digit of the answer. 
Result so far: 433.523809
If we subtract 189 from 200, we get 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Let's proceed to step 11:
The number 21 fits into 110 5 times, leaving a remainder of 5.
The next digit of our result is 5. 
Result so far: 433.5238095
Subtract 105 from 110 to get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

On to step 12:
21 goes into 50 2 times with a remainder of 8.
Use 2 as the next digit of our solution. 
Result so far: 433.52380952
Subtract 42 from 50 to 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.

Our division results in 433.52380952 with a remaining 8e-09.