We look at the division of 863844 by 21 
We want to figure out the number of times 863844 can be divided by 21.

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
If we take 0 away from 8, we end up with 8.
Append the next digit (6) from the dividend to 8 and continue with: 86 / 21

Advancing to step 2:
21 can be fit into 86 4 times, resulting in a remainder of 2.
The next digit of our result is 4. 
Result so far: 4.0
If we subtract 84 from 86, we get 2.
Grab the next digit (3) from the dividend, add it to 2, then carry on: 23 / 21

Moving on to step 3:
23 divided by 21 is 1 with a remainder of 2.
The number 1 becomes the next digit in our result. 
Result so far: 41.0
If we subtract 21 from 23, we get 2.
Bring next digit (8) of the dividend behind the 2 and repeat the process: 28 / 21

Moving on to step 4:
The number 21 fits into 28 1 times, leaving a remainder of 7.
The number 1 becomes the next digit in our result. 
Result so far: 411.0
If we take 21 away from 28, we end up with 7.
Grab the next digit (4) from the dividend, add it to 7, then carry on: 74 / 21

Step 5:
21 goes into 74 3 times with a remainder of 11.
Write down 3 as next digit of the result. 
Result so far: 4113.0
The remainder is 11 after subtracting 63 from 74.
Take the next digit (4) from the dividend and append it to 11, then repeat: 114 / 21

Going ahead to step 6:
When dividing 114 by 21, we get 5 with a remainder of 9.
The number 5 becomes the next digit in our result. 
Result so far: 41135.0
If we subtract 105 from 114, we get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Moving on to step 7:
The number 21 fits into 90 4 times, leaving a remainder of 6.
Use 4 as the next digit of our solution. 
Result so far: 41135.4
Subtracting 84 from 90 leaves us with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Moving on to step 8:
21 can be fit into 60 2 times, resulting in a remainder of 18.
Write down 2 as next digit of the result. 
Result so far: 41135.42
If we subtract 42 from 60, we get 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Moving on to step 9:
If we divide 180 by 21, we get 8 and a remainder of 12.
Put 8 as the next digit of the answer. 
Result so far: 41135.428
If we take 168 away from 180, we end up 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.

Step 10:
When dividing 120 by 21, we get 5 with a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 41135.4285
Deduct 105 from 120 and we're left 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.

Step 11:
If we divide 150 by 21, we get 7 and a remainder of 3.
Put 7 as the next digit of the answer. 
Result so far: 41135.42857
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.

Advancing to step 12:
If we divide 30 by 21, we get 1 and a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 41135.428571
Subtract 21 from 30 to get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Advancing to step 13:
The number 21 fits into 90 4 times, leaving a remainder of 6.
The next digit of our result is 4. 
Result so far: 41135.4285714
If we take 84 away from 90, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Advancing to step 14:
The number 21 fits into 60 2 times, leaving a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 41135.42857142
If we take 42 away from 60, we end up 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.

Our division results in 41135.42857142 with a remaining 1.8e-08.