We look at the division of 39638868 by 21 
Let's see how many times 21 fits into 39638868.

Step 1:
21 can be fit into 3 0 times, resulting in a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we subtract 0 from 3, we get 3.
Grab the next digit (9) from the dividend, add it to 3, then carry on: 39 / 21

Going ahead to step 2:
21 goes into 39 1 times with a remainder of 18.
The next digit of our result is 1. 
Result so far: 1.0
If we take 21 away from 39, we end up with 18.
Grab the next digit (6) from the dividend, add it to 18, then carry on: 186 / 21

Going ahead to step 3:
186 divided by 21 is 8 with a remainder of 18.
The number 8 becomes the next digit in our result. 
Result so far: 18.0
Deduct 168 from 186 and we're left with 18.
Take the next digit (3) from the dividend and append it to 18, then repeat: 183 / 21

On to step 4:
When dividing 183 by 21, we get 8 with a remainder of 15.
Use 8 as the next digit of our solution. 
Result so far: 188.0
Subtracting 168 from 183 leaves us with 15.
Include the next digit (8) from the dividend after 15, then repeat: 158 / 21

Moving on to step 5:
The number 21 fits into 158 7 times, leaving a remainder of 11.
Put 7 as the next digit of the answer. 
Result so far: 1887.0
Subtract 147 from 158 to get 11.
Include the next digit (8) from the dividend after 11, then repeat: 118 / 21

Going ahead to step 6:
If we divide 118 by 21, we get 5 and a remainder of 13.
The next digit of our result is 5. 
Result so far: 18875.0
If we subtract 105 from 118, we get 13.
Bring next digit (6) of the dividend behind the 13 and repeat the process: 136 / 21

Let's proceed to step 7:
21 can be fit into 136 6 times, resulting in a remainder of 10.
Write down 6 as next digit of the result. 
Result so far: 188756.0
Subtract 126 from 136 to get 10.
Include the next digit (8) from the dividend after 10, then repeat: 108 / 21

Let's proceed to step 8:
21 goes into 108 5 times with a remainder of 3.
Put 5 as the next digit of the answer. 
Result so far: 1887565.0
Subtract 105 from 108 to get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Step 9:
When dividing 30 by 21, we get 1 with a remainder of 9.
The next digit of our result is 1. 
Result so far: 1887565.1
The remainder is 9 after subtracting 21 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Going ahead to step 10:
21 can be fit into 90 4 times, resulting in a remainder of 6.
Use 4 as the next digit of our solution. 
Result so far: 1887565.14
Subtract 84 from 90 to 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.

Going ahead to step 11:
21 can be fit into 60 2 times, resulting in a remainder of 18.
The number 2 becomes the next digit in our result. 
Result so far: 1887565.142
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.

Moving on to step 12:
21 can be fit into 180 8 times, resulting in a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 1887565.1428
The remainder is 12 after subtracting 168 from 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Let's proceed to step 13:
If we divide 120 by 21, we get 5 and a remainder of 15.
The next digit of our result is 5. 
Result so far: 1887565.14285
Subtracting 105 from 120 leaves us 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 14:
21 goes into 150 7 times with a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 1887565.142857
Subtract 147 from 150 to get 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 15:
30 divided by 21 is 1 with a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 1887565.1428571
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 16:
21 goes into 90 4 times with a remainder of 6.
The next digit of our result is 4. 
Result so far: 1887565.14285714
The remainder is 6 after subtracting 84 from 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

The final result is 1887565.14285714 with a remainder of 6e-09.