We look at the division of 399373 by 75 
We want to figure out the number of times 399373 can be divided by 75.

On to step 1:
75 can be fit into 3 0 times, resulting in a remainder of 3.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 3 leaves us with 3.
Include the next digit (9) from the dividend after 3, then repeat: 39 / 75

Moving on to step 2:
75 can be fit into 39 0 times, resulting in a remainder of 39.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 39 and we're left with 39.
Take the next digit (9) from the dividend and append it to 39, then repeat: 399 / 75

Let's proceed to step 3:
75 goes into 399 5 times with a remainder of 24.
Record the quotient 5 as the next digit in the result. 
Result so far: 5.0
Subtracting 375 from 399 leaves us with 24.
Grab the next digit (3) from the dividend, add it to 24, then carry on: 243 / 75

Moving on to step 4:
243 divided by 75 is 3 with a remainder of 18.
The number 3 becomes the next digit in our result. 
Result so far: 53.0
Subtract 225 from 243 to get 18.
Append the next digit (7) from the dividend to 18 and continue with: 187 / 75

Step 5:
The number 75 fits into 187 2 times, leaving a remainder of 37.
Use 2 as the next digit of our solution. 
Result so far: 532.0
If we take 150 away from 187, we end up with 37.
Append the next digit (3) from the dividend to 37 and continue with: 373 / 75

Moving on to step 6:
If we divide 373 by 75, we get 4 and a remainder of 73.
Write down 4 as next digit of the result. 
Result so far: 5324.0
Subtract 300 from 373 to get 73.
Since there are no more digits in the dividend, we add a zero to the remainder making it 730, and continue the process.

On to step 7:
730 divided by 75 is 9 with a remainder of 55.
Use 9 as the next digit of our solution. 
Result so far: 5324.9
Subtracting 675 from 730 leaves us with 55.
Since there are no more digits in the dividend, we add a zero to the remainder making it 550, and continue the process.

Moving on to step 8:
When dividing 550 by 75, we get 7 with a remainder of 25.
The number 7 becomes the next digit in our result. 
Result so far: 5324.97
If we subtract 525 from 550, we get 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Step 9:
75 can be fit into 250 3 times, resulting in a remainder of 25.
Record the quotient 3 as the next digit in the result. 
Result so far: 5324.973
The remainder is 25 after subtracting 225 from 250.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

On to step 10:
If we divide 250 by 75, we get 3 and a remainder of 25.
Put 3 as the next digit of the answer. 
Result so far: 5324.9733
If we take 225 away from 250, we end up with 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

The final result is 5324.9733 with a remainder of 0.00025.