Let's divide 86404 by 15
Let's see how many times 15 fits into 86404.

Advancing to step 1:
15 can be fit into 8 0 times, resulting in a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we subtract 0 from 8, we get 8.
Take the next digit (6) from the dividend and append it to 8, then repeat: 86 / 15

Going ahead to step 2:
15 goes into 86 5 times with a remainder of 11.
The number 5 becomes the next digit in our result. 
Result so far: 5.0
If we take 75 away from 86, we end up with 11.
Bring next digit (4) of the dividend behind the 11 and repeat the process: 114 / 15

Step 3:
15 can be fit into 114 7 times, resulting in a remainder of 9.
Use 7 as the next digit of our solution. 
Result so far: 57.0
Subtract 105 from 114 to get 9.
Append the next digit (0) from the dividend to 9 and continue with: 90 / 15

Let's proceed to step 4:
If we divide 90 by 15, we get 6 and a remainder of 0.
Write down 6 as next digit of the result. 
Result so far: 576.0
If we subtract 90 from 90, we get 0.
Fetch the next digit (4) from the dividend, attach it to 0 and continue: 4 / 15

On to step 5:
15 goes into 4 0 times with a remainder of 4.
The number 0 becomes the next digit in our result. 
Result so far: 5760.0
If we subtract 0 from 4, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Step 6:
When dividing 40 by 15, we get 2 with a remainder of 10.
Put 2 as the next digit of the answer. 
Result so far: 5760.2
Subtracting 30 from 40 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 7:
The number 15 fits into 100 6 times, leaving a remainder of 10.
Record the quotient 6 as the next digit in the result. 
Result so far: 5760.26
Deduct 90 from 100 and we're left with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Let's proceed to step 8:
The number 15 fits into 100 6 times, leaving a remainder of 10.
Write down 6 as next digit of the result. 
Result so far: 5760.266
If we take 90 away from 100, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

After the division, we end up with 5760.266 and a remainder of 0.001.