We look at the division of 39893391 by 21 
Our goal is to divide 39893391 by 21.

Going ahead to step 1:
When dividing 3 by 21, we get 0 with a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 3 and we're left with 3.
Append the next digit (9) from the dividend to 3 and continue with: 39 / 21

Step 2:
If we divide 39 by 21, we get 1 and a remainder of 18.
Use 1 as the next digit of our solution. 
Result so far: 1.0
The remainder is 18 after subtracting 21 from 39.
Bring next digit (8) of the dividend behind the 18 and repeat the process: 188 / 21

Going ahead to step 3:
If we divide 188 by 21, we get 8 and a remainder of 20.
The number 8 becomes the next digit in our result. 
Result so far: 18.0
Deduct 168 from 188 and we're left with 20.
Bring next digit (9) of the dividend behind the 20 and repeat the process: 209 / 21

Going ahead to step 4:
When dividing 209 by 21, we get 9 with a remainder of 20.
Write down 9 as next digit of the result. 
Result so far: 189.0
Subtract 189 from 209 to get 20.
Take the next digit (3) from the dividend and append it to 20, then repeat: 203 / 21

Moving on to step 5:
When dividing 203 by 21, we get 9 with a remainder of 14.
Write down 9 as next digit of the result. 
Result so far: 1899.0
If we take 189 away from 203, we end up with 14.
Fetch the next digit (3) from the dividend, attach it to 14 and continue: 143 / 21

On to step 6:
The number 21 fits into 143 6 times, leaving a remainder of 17.
Record the quotient 6 as the next digit in the result. 
Result so far: 18996.0
Subtracting 126 from 143 leaves us with 17.
Bring next digit (9) of the dividend behind the 17 and repeat the process: 179 / 21

Going ahead to step 7:
21 goes into 179 8 times with a remainder of 11.
Use 8 as the next digit of our solution. 
Result so far: 189968.0
Subtract 168 from 179 to get 11.
Include the next digit (1) from the dividend after 11, then repeat: 111 / 21

Moving on to step 8:
21 goes into 111 5 times with a remainder of 6.
Record the quotient 5 as the next digit in the result. 
Result so far: 1899685.0
If we take 105 away from 111, 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.

Let's proceed to step 9:
The number 21 fits into 60 2 times, leaving a remainder of 18.
Record the quotient 2 as the next digit in the result. 
Result so far: 1899685.2
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.

Going ahead to step 10:
21 can be fit into 180 8 times, resulting in a remainder of 12.
Write down 8 as next digit of the result. 
Result so far: 1899685.28
Subtract 168 from 180 to get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Advancing to step 11:
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: 1899685.285
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.

Moving on to step 12:
When dividing 150 by 21, we get 7 with a remainder of 3.
Write down 7 as next digit of the result. 
Result so far: 1899685.2857
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.

Going ahead to step 13:
21 goes into 30 1 times with a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 1899685.28571
Subtracting 21 from 30 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.

Advancing to step 14:
If we divide 90 by 21, we get 4 and a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 1899685.285714
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.

On to step 15:
If we divide 60 by 21, we get 2 and a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 1899685.2857142
Subtract 42 from 60 to 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 16:
If we divide 180 by 21, we get 8 and a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 1899685.28571428
Subtract 168 from 180 to get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Our division results in 1899685.28571428 with a remaining 1.2e-08.