399138 ÷ 84 
Our goal is to divide 399138 by 84.

Going ahead to step 1:
3 divided by 84 is 0 with a remainder of 3.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 3, we get 3.
Append the next digit (9) from the dividend to 3 and continue with: 39 / 84

Advancing to step 2:
84 can be fit into 39 0 times, resulting in a remainder of 39.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 39, we end up with 39.
Include the next digit (9) from the dividend after 39, then repeat: 399 / 84

Going ahead to step 3:
84 goes into 399 4 times with a remainder of 63.
Record the quotient 4 as the next digit in the result. 
Result so far: 4.0
Subtract 336 from 399 to get 63.
Take the next digit (1) from the dividend and append it to 63, then repeat: 631 / 84

Advancing to step 4:
When dividing 631 by 84, we get 7 with a remainder of 43.
Put 7 as the next digit of the answer. 
Result so far: 47.0
Subtracting 588 from 631 leaves us with 43.
Fetch the next digit (3) from the dividend, attach it to 43 and continue: 433 / 84

Let's proceed to step 5:
84 can be fit into 433 5 times, resulting in a remainder of 13.
The number 5 becomes the next digit in our result. 
Result so far: 475.0
Deduct 420 from 433 and we're left with 13.
Take the next digit (8) from the dividend and append it to 13, then repeat: 138 / 84

On to step 6:
84 goes into 138 1 times with a remainder of 54.
Write down 1 as next digit of the result. 
Result so far: 4751.0
If we subtract 84 from 138, we get 54.
Since there are no more digits in the dividend, we add a zero to the remainder making it 540, and continue the process.

Let's proceed to step 7:
When dividing 540 by 84, we get 6 with a remainder of 36.
Put 6 as the next digit of the answer. 
Result so far: 4751.6
Subtract 504 from 540 to get 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

On to step 8:
The number 84 fits into 360 4 times, leaving a remainder of 24.
Write down 4 as next digit of the result. 
Result so far: 4751.64
If we take 336 away from 360, we end up with 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

Step 9:
84 goes into 240 2 times with a remainder of 72.
Put 2 as the next digit of the answer. 
Result so far: 4751.642
If we subtract 168 from 240, we get 72.
Since there are no more digits in the dividend, we add a zero to the remainder making it 720, and continue the process.

Let's proceed to step 10:
The number 84 fits into 720 8 times, leaving a remainder of 48.
Write down 8 as next digit of the result. 
Result so far: 4751.6428
The remainder is 48 after subtracting 672 from 720.
Since there are no more digits in the dividend, we add a zero to the remainder making it 480, and continue the process.

Step 11:
The number 84 fits into 480 5 times, leaving a remainder of 60.
The number 5 becomes the next digit in our result. 
Result so far: 4751.64285
Subtracting 420 from 480 leaves us with 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

Advancing to step 12:
The number 84 fits into 600 7 times, leaving a remainder of 12.
Put 7 as the next digit of the answer. 
Result so far: 4751.642857
Subtracting 588 from 600 leaves us with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Going ahead to step 13:
84 can be fit into 120 1 times, resulting in a remainder of 36.
Record the quotient 1 as the next digit in the result. 
Result so far: 4751.6428571
Subtracting 84 from 120 leaves us with 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

Going ahead to step 14:
The number 84 fits into 360 4 times, leaving a remainder of 24.
Write down 4 as next digit of the result. 
Result so far: 4751.64285714
Subtracting 336 from 360 leaves us with 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

The final outcome is 4751.64285714, with a leftover of 2.4e-08.