399431 ÷ 4 
Our goal is to divide 399431 by 4.

Going ahead to step 1:
3 divided by 4 is 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.
Grab the next digit (9) from the dividend, add it to 3, then carry on: 39 / 4

On to step 2:
4 goes into 39 9 times with a remainder of 3.
Write down 9 as next digit of the result. 
Result so far: 9.0
Deduct 36 from 39 and we're left with 3.
Include the next digit (9) from the dividend after 3, then repeat: 39 / 4

Let's proceed to step 3:
The number 4 fits into 39 9 times, leaving a remainder of 3.
Write down 9 as next digit of the result. 
Result so far: 99.0
Subtract 36 from 39 to get 3.
Include the next digit (4) from the dividend after 3, then repeat: 34 / 4

Let's proceed to step 4:
4 goes into 34 8 times with a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 998.0
Subtract 32 from 34 to get 2.
Take the next digit (3) from the dividend and append it to 2, then repeat: 23 / 4

Let's proceed to step 5:
If we divide 23 by 4, we get 5 and a remainder of 3.
The next digit of our result is 5. 
Result so far: 9985.0
If we take 20 away from 23, we end up with 3.
Include the next digit (1) from the dividend after 3, then repeat: 31 / 4

On to step 6:
4 goes into 31 7 times with a remainder of 3.
Put 7 as the next digit of the answer. 
Result so far: 99857.0
If we take 28 away from 31, we end up 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.

On to step 7:
When dividing 30 by 4, we get 7 with a remainder of 2.
The next digit of our result is 7. 
Result so far: 99857.7
Deduct 28 from 30 and we're left with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Advancing to step 8:
If we divide 20 by 4, we get 5 and a remainder of 0.
Record the quotient 5 as the next digit in the result. 
Result so far: 99857.75
Subtract 20 from 20 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 9:
The number 4 fits into 0 0 times, leaving a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 99857.75
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 10:
If we divide 0 by 4, we get 0 and a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 99857.75
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

After the division, we end up with 99857.75 and a remainder of 0.0.