855220 divided by 21 
We're looking to find how many times 21 goes into 855220.

Step 1:
If we divide 8 by 21, we get 0 and a remainder of 8.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 8, we end up with 8.
Append the next digit (5) from the dividend to 8 and continue with: 85 / 21

On to step 2:
21 can be fit into 85 4 times, resulting in a remainder of 1.
Use 4 as the next digit of our solution. 
Result so far: 4.0
Subtracting 84 from 85 leaves us with 1.
Include the next digit (5) from the dividend after 1, then repeat: 15 / 21

Advancing to step 3:
21 goes into 15 0 times with a remainder of 15.
Record the quotient 0 as the next digit in the result. 
Result so far: 40.0
Subtracting 0 from 15 leaves us with 15.
Bring next digit (2) of the dividend behind the 15 and repeat the process: 152 / 21

Step 4:
If we divide 152 by 21, we get 7 and a remainder of 5.
The number 7 becomes the next digit in our result. 
Result so far: 407.0
If we subtract 147 from 152, we get 5.
Bring next digit (2) of the dividend behind the 5 and repeat the process: 52 / 21

Moving on to step 5:
52 divided by 21 is 2 with a remainder of 10.
Put 2 as the next digit of the answer. 
Result so far: 4072.0
The remainder is 10 after subtracting 42 from 52.
Grab the next digit (0) from the dividend, add it to 10, then carry on: 100 / 21

On to step 6:
When dividing 100 by 21, we get 4 with a remainder of 16.
Write down 4 as next digit of the result. 
Result so far: 40724.0
The remainder is 16 after subtracting 84 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Moving on to step 7:
When dividing 160 by 21, we get 7 with a remainder of 13.
Record the quotient 7 as the next digit in the result. 
Result so far: 40724.7
Subtract 147 from 160 to get 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Step 8:
The number 21 fits into 130 6 times, leaving a remainder of 4.
The next digit of our result is 6. 
Result so far: 40724.76
Subtracting 126 from 130 leaves us with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Step 9:
40 divided by 21 is 1 with a remainder of 19.
Record the quotient 1 as the next digit in the result. 
Result so far: 40724.761
Deduct 21 from 40 and we're left with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Going ahead to step 10:
The number 21 fits into 190 9 times, leaving a remainder of 1.
Record the quotient 9 as the next digit in the result. 
Result so far: 40724.7619
Subtracting 189 from 190 leaves us with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Going ahead to step 11:
The number 21 fits into 10 0 times, leaving a remainder of 10.
Put 0 as the next digit of the answer. 
Result so far: 40724.7619
Subtracting 0 from 10 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Going ahead to step 12:
The number 21 fits into 100 4 times, leaving a remainder of 16.
The number 4 becomes the next digit in our result. 
Result so far: 40724.761904
The remainder is 16 after subtracting 84 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Going ahead to step 13:
If we divide 160 by 21, we get 7 and a remainder of 13.
Record the quotient 7 as the next digit in the result. 
Result so far: 40724.7619047
If we take 147 away from 160, we end up with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

On to step 14:
21 can be fit into 130 6 times, resulting in a remainder of 4.
Put 6 as the next digit of the answer. 
Result so far: 40724.76190476
Deduct 126 from 130 and we're left with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

The final result is 40724.76190476 with a remainder of 4e-09.