We divide 15860204 by 399
We're looking to find how many times 399 goes into 15860204.

Moving on to step 1:
399 goes into 1 0 times with a remainder of 1.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 1 leaves us with 1.
Include the next digit (5) from the dividend after 1, then repeat: 15 / 399

Let's proceed to step 2:
15 divided by 399 is 0 with a remainder of 15.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 15 and we're left with 15.
Fetch the next digit (8) from the dividend, attach it to 15 and continue: 158 / 399

Advancing to step 3:
If we divide 158 by 399, we get 0 and a remainder of 158.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 158 leaves us with 158.
Include the next digit (6) from the dividend after 158, then repeat: 1586 / 399

On to step 4:
When dividing 1586 by 399, we get 3 with a remainder of 389.
The number 3 becomes the next digit in our result. 
Result so far: 3.0
Subtract 1197 from 1586 to get 389.
Include the next digit (0) from the dividend after 389, then repeat: 3890 / 399

On to step 5:
If we divide 3890 by 399, we get 9 and a remainder of 299.
The number 9 becomes the next digit in our result. 
Result so far: 39.0
Subtract 3591 from 3890 to get 299.
Include the next digit (2) from the dividend after 299, then repeat: 2992 / 399

Step 6:
If we divide 2992 by 399, we get 7 and a remainder of 199.
The number 7 becomes the next digit in our result. 
Result so far: 397.0
Subtracting 2793 from 2992 leaves us with 199.
Bring next digit (0) of the dividend behind the 199 and repeat the process: 1990 / 399

On to step 7:
1990 divided by 399 is 4 with a remainder of 394.
The number 4 becomes the next digit in our result. 
Result so far: 3974.0
Deduct 1596 from 1990 and we're left with 394.
Include the next digit (4) from the dividend after 394, then repeat: 3944 / 399

Let's proceed to step 8:
When dividing 3944 by 399, we get 9 with a remainder of 353.
The number 9 becomes the next digit in our result. 
Result so far: 39749.0
If we take 3591 away from 3944, we end up with 353.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3530, and continue the process.

Going ahead to step 9:
If we divide 3530 by 399, we get 8 and a remainder of 338.
Record the quotient 8 as the next digit in the result. 
Result so far: 39749.8
If we subtract 3192 from 3530, we get 338.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3380, and continue the process.

Let's proceed to step 10:
The number 399 fits into 3380 8 times, leaving a remainder of 188.
Write down 8 as next digit of the result. 
Result so far: 39749.88
If we subtract 3192 from 3380, we get 188.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1880, and continue the process.

The final outcome is 39749.88, with a leftover of 0.188.