129399 ÷ 84 
Our goal is to divide 129399 by 84.

On to step 1:
1 divided by 84 is 0 with a remainder of 1.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 1 and we're left with 1.
Append the next digit (2) from the dividend to 1 and continue with: 12 / 84

Step 2:
84 can be fit into 12 0 times, resulting in a remainder of 12.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 12 and we're left with 12.
Fetch the next digit (9) from the dividend, attach it to 12 and continue: 129 / 84

Moving on to step 3:
84 can be fit into 129 1 times, resulting in a remainder of 45.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Subtract 84 from 129 to get 45.
Bring next digit (3) of the dividend behind the 45 and repeat the process: 453 / 84

On to step 4:
The number 84 fits into 453 5 times, leaving a remainder of 33.
The next digit of our result is 5. 
Result so far: 15.0
The remainder is 33 after subtracting 420 from 453.
Include the next digit (9) from the dividend after 33, then repeat: 339 / 84

Advancing to step 5:
The number 84 fits into 339 4 times, leaving a remainder of 3.
The number 4 becomes the next digit in our result. 
Result so far: 154.0
Subtract 336 from 339 to get 3.
Take the next digit (9) from the dividend and append it to 3, then repeat: 39 / 84

Going ahead to step 6:
The number 84 fits into 39 0 times, leaving a remainder of 39.
Record the quotient 0 as the next digit in the result. 
Result so far: 1540.0
Deduct 0 from 39 and we're left with 39.
Since there are no more digits in the dividend, we add a zero to the remainder making it 390, and continue the process.

Let's proceed to step 7:
When dividing 390 by 84, we get 4 with a remainder of 54.
Write down 4 as next digit of the result. 
Result so far: 1540.4
Deduct 336 from 390 and we're left with 54.
Since there are no more digits in the dividend, we add a zero to the remainder making it 540, and continue the process.

On to step 8:
84 can be fit into 540 6 times, resulting in a remainder of 36.
Put 6 as the next digit of the answer. 
Result so far: 1540.46
Subtracting 504 from 540 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.

Step 9:
84 goes into 360 4 times with a remainder of 24.
Write down 4 as next digit of the result. 
Result so far: 1540.464
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.

Moving on to step 10:
If we divide 240 by 84, we get 2 and a remainder of 72.
Put 2 as the next digit of the answer. 
Result so far: 1540.4642
If we take 168 away from 240, we end up with 72.
Since there are no more digits in the dividend, we add a zero to the remainder making it 720, and continue the process.

On to step 11:
84 can be fit into 720 8 times, resulting in a remainder of 48.
Write down 8 as next digit of the result. 
Result so far: 1540.46428
If we take 672 away from 720, we end up with 48.
Since there are no more digits in the dividend, we add a zero to the remainder making it 480, and continue the process.

Step 12:
If we divide 480 by 84, we get 5 and a remainder of 60.
Record the quotient 5 as the next digit in the result. 
Result so far: 1540.464285
Subtract 420 from 480 to get 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 13:
When dividing 600 by 84, we get 7 with a remainder of 12.
Write down 7 as next digit of the result. 
Result so far: 1540.4642857
The remainder is 12 after subtracting 588 from 600.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

On to step 14:
If we divide 120 by 84, we get 1 and a remainder of 36.
Record the quotient 1 as the next digit in the result. 
Result so far: 1540.46428571
The remainder is 36 after subtracting 84 from 120.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

In conclusion, the division gives 1540.46428571 with a balance of 3.6e-08.