We're dividing 857565 by 21 
We want to figure out the number of times 857565 can be divided by 21.

Going ahead to step 1:
If we divide 8 by 21, we get 0 and a remainder of 8.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 8 after subtracting 0 from 8.
Bring next digit (5) of the dividend behind the 8 and repeat the process: 85 / 21

On to step 2:
If we divide 85 by 21, we get 4 and a remainder of 1.
Put 4 as the next digit of the answer. 
Result so far: 4.0
Subtracting 84 from 85 leaves us with 1.
Append the next digit (7) from the dividend to 1 and continue with: 17 / 21

On to step 3:
The number 21 fits into 17 0 times, leaving a remainder of 17.
Put 0 as the next digit of the answer. 
Result so far: 40.0
If we take 0 away from 17, we end up with 17.
Grab the next digit (5) from the dividend, add it to 17, then carry on: 175 / 21

Step 4:
21 goes into 175 8 times with a remainder of 7.
Record the quotient 8 as the next digit in the result. 
Result so far: 408.0
The remainder is 7 after subtracting 168 from 175.
Include the next digit (6) from the dividend after 7, then repeat: 76 / 21

On to step 5:
21 can be fit into 76 3 times, resulting in a remainder of 13.
The number 3 becomes the next digit in our result. 
Result so far: 4083.0
If we take 63 away from 76, we end up with 13.
Grab the next digit (5) from the dividend, add it to 13, then carry on: 135 / 21

Going ahead to step 6:
When dividing 135 by 21, we get 6 with a remainder of 9.
The next digit of our result is 6. 
Result so far: 40836.0
Subtracting 126 from 135 leaves us with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

On to step 7:
If we divide 90 by 21, we get 4 and a remainder of 6.
Use 4 as the next digit of our solution. 
Result so far: 40836.4
If we subtract 84 from 90, we get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Step 8:
If we divide 60 by 21, we get 2 and a remainder of 18.
The next digit of our result is 2. 
Result so far: 40836.42
The remainder is 18 after subtracting 42 from 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Let's proceed to step 9:
If we divide 180 by 21, we get 8 and a remainder of 12.
Write down 8 as next digit of the result. 
Result so far: 40836.428
Subtracting 168 from 180 leaves us with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Going ahead to step 10:
21 can be fit into 120 5 times, resulting in a remainder of 15.
Put 5 as the next digit of the answer. 
Result so far: 40836.4285
If we take 105 away from 120, we end up with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Advancing to step 11:
When dividing 150 by 21, we get 7 with a remainder of 3.
Put 7 as the next digit of the answer. 
Result so far: 40836.42857
Subtracting 147 from 150 leaves us with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Moving on to step 12:
When dividing 30 by 21, we get 1 with a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 40836.428571
Deduct 21 from 30 and we're left with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

On to step 13:
If we divide 90 by 21, we get 4 and a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 40836.4285714
If we subtract 84 from 90, we get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Step 14:
If we divide 60 by 21, we get 2 and a remainder of 18.
Put 2 as the next digit of the answer. 
Result so far: 40836.42857142
Deduct 42 from 60 and we're left with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

The final result is 40836.42857142 with a remainder of 1.8e-08.