We look at the division of 39243920 by 321 
Let's see how many times 321 fits into 39243920.

Step 1:
3 divided by 321 is 0 with a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 3, we get 3.
Take the next digit (9) from the dividend and append it to 3, then repeat: 39 / 321

Moving on to step 2:
39 divided by 321 is 0 with a remainder of 39.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 39, we end up with 39.
Take the next digit (2) from the dividend and append it to 39, then repeat: 392 / 321

On to step 3:
If we divide 392 by 321, we get 1 and a remainder of 71.
Write down 1 as next digit of the result. 
Result so far: 1.0
Subtract 321 from 392 to get 71.
Append the next digit (4) from the dividend to 71 and continue with: 714 / 321

Step 4:
When dividing 714 by 321, we get 2 with a remainder of 72.
Write down 2 as next digit of the result. 
Result so far: 12.0
If we subtract 642 from 714, we get 72.
Bring next digit (3) of the dividend behind the 72 and repeat the process: 723 / 321

Let's proceed to step 5:
723 divided by 321 is 2 with a remainder of 81.
Put 2 as the next digit of the answer. 
Result so far: 122.0
If we take 642 away from 723, we end up with 81.
Fetch the next digit (9) from the dividend, attach it to 81 and continue: 819 / 321

Going ahead to step 6:
321 can be fit into 819 2 times, resulting in a remainder of 177.
The next digit of our result is 2. 
Result so far: 1222.0
If we subtract 642 from 819, we get 177.
Append the next digit (2) from the dividend to 177 and continue with: 1772 / 321

Moving on to step 7:
321 goes into 1772 5 times with a remainder of 167.
Use 5 as the next digit of our solution. 
Result so far: 12225.0
Subtract 1605 from 1772 to get 167.
Bring next digit (0) of the dividend behind the 167 and repeat the process: 1670 / 321

Advancing to step 8:
321 goes into 1670 5 times with a remainder of 65.
Put 5 as the next digit of the answer. 
Result so far: 122255.0
Subtract 1605 from 1670 to get 65.
Since there are no more digits in the dividend, we add a zero to the remainder making it 650, and continue the process.

On to step 9:
321 can be fit into 650 2 times, resulting in a remainder of 8.
Use 2 as the next digit of our solution. 
Result so far: 122255.2
The remainder is 8 after subtracting 642 from 650.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Let's proceed to step 10:
The number 321 fits into 80 0 times, leaving a remainder of 80.
Record the quotient 0 as the next digit in the result. 
Result so far: 122255.2
Deduct 0 from 80 and we're left with 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Step 11:
If we divide 800 by 321, we get 2 and a remainder of 158.
Put 2 as the next digit of the answer. 
Result so far: 122255.202
Deduct 642 from 800 and we're left with 158.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1580, and continue the process.

Advancing to step 12:
321 can be fit into 1580 4 times, resulting in a remainder of 296.
The number 4 becomes the next digit in our result. 
Result so far: 122255.2024
If we subtract 1284 from 1580, we get 296.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2960, and continue the process.

Moving on to step 13:
321 can be fit into 2960 9 times, resulting in a remainder of 71.
The number 9 becomes the next digit in our result. 
Result so far: 122255.20249
Subtracting 2889 from 2960 leaves us with 71.
Since there are no more digits in the dividend, we add a zero to the remainder making it 710, and continue the process.

Moving on to step 14:
710 divided by 321 is 2 with a remainder of 68.
Use 2 as the next digit of our solution. 
Result so far: 122255.202492
Subtract 642 from 710 to get 68.
Since there are no more digits in the dividend, we add a zero to the remainder making it 680, and continue the process.

Step 15:
If we divide 680 by 321, we get 2 and a remainder of 38.
The next digit of our result is 2. 
Result so far: 122255.2024922
If we take 642 away from 680, we end up with 38.
Since there are no more digits in the dividend, we add a zero to the remainder making it 380, and continue the process.

The final outcome is 122255.2024922, with a leftover of 3.8e-07.