12885429 ÷ 839 
Let's see how many times 839 fits into 12885429.

Going ahead to step 1:
If we divide 1 by 839, we get 0 and a remainder of 1.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 1 leaves us with 1.
Take the next digit (2) from the dividend and append it to 1, then repeat: 12 / 839

Advancing to step 2:
839 can be fit into 12 0 times, resulting in a remainder of 12.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 12 and we're left with 12.
Append the next digit (8) from the dividend to 12 and continue with: 128 / 839

Going ahead to step 3:
When dividing 128 by 839, we get 0 with a remainder of 128.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 128 to get 128.
Append the next digit (8) from the dividend to 128 and continue with: 1288 / 839

On to step 4:
1288 divided by 839 is 1 with a remainder of 449.
Put 1 as the next digit of the answer. 
Result so far: 1.0
Subtracting 839 from 1288 leaves us with 449.
Take the next digit (5) from the dividend and append it to 449, then repeat: 4495 / 839

Let's proceed to step 5:
839 goes into 4495 5 times with a remainder of 300.
The next digit of our result is 5. 
Result so far: 15.0
If we take 4195 away from 4495, we end up with 300.
Include the next digit (4) from the dividend after 300, then repeat: 3004 / 839

Advancing to step 6:
839 can be fit into 3004 3 times, resulting in a remainder of 487.
Put 3 as the next digit of the answer. 
Result so far: 153.0
If we subtract 2517 from 3004, we get 487.
Bring next digit (2) of the dividend behind the 487 and repeat the process: 4872 / 839

Let's proceed to step 7:
839 can be fit into 4872 5 times, resulting in a remainder of 677.
The next digit of our result is 5. 
Result so far: 1535.0
Subtract 4195 from 4872 to get 677.
Fetch the next digit (9) from the dividend, attach it to 677 and continue: 6779 / 839

Step 8:
When dividing 6779 by 839, we get 8 with a remainder of 67.
Use 8 as the next digit of our solution. 
Result so far: 15358.0
Deduct 6712 from 6779 and we're left with 67.
Since there are no more digits in the dividend, we add a zero to the remainder making it 670, and continue the process.

On to step 9:
839 can be fit into 670 0 times, resulting in a remainder of 670.
The number 0 becomes the next digit in our result. 
Result so far: 15358.0
If we take 0 away from 670, we end up with 670.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6700, and continue the process.

On to step 10:
If we divide 6700 by 839, we get 7 and a remainder of 827.
Record the quotient 7 as the next digit in the result. 
Result so far: 15358.07
If we take 5873 away from 6700, we end up with 827.
Since there are no more digits in the dividend, we add a zero to the remainder making it 8270, and continue the process.

Let's proceed to step 11:
When dividing 8270 by 839, we get 9 with a remainder of 719.
Write down 9 as next digit of the result. 
Result so far: 15358.079
Subtracting 7551 from 8270 leaves us with 719.
Since there are no more digits in the dividend, we add a zero to the remainder making it 7190, and continue the process.

On to step 12:
If we divide 7190 by 839, we get 8 and a remainder of 478.
Use 8 as the next digit of our solution. 
Result so far: 15358.0798
Subtract 6712 from 7190 to get 478.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4780, and continue the process.

Let's proceed to step 13:
4780 divided by 839 is 5 with a remainder of 585.
Write down 5 as next digit of the result. 
Result so far: 15358.07985
The remainder is 585 after subtracting 4195 from 4780.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5850, and continue the process.

Let's proceed to step 14:
839 goes into 5850 6 times with a remainder of 816.
Use 6 as the next digit of our solution. 
Result so far: 15358.079856
If we take 5034 away from 5850, we end up with 816.
Since there are no more digits in the dividend, we add a zero to the remainder making it 8160, and continue the process.

Advancing to step 15:
When dividing 8160 by 839, we get 9 with a remainder of 609.
The number 9 becomes the next digit in our result. 
Result so far: 15358.0798569
If we subtract 7551 from 8160, we get 609.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6090, and continue the process.

Going ahead to step 16:
When dividing 6090 by 839, we get 7 with a remainder of 217.
Record the quotient 7 as the next digit in the result. 
Result so far: 15358.07985697
Subtract 5873 from 6090 to get 217.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2170, and continue the process.

The final result is 15358.07985697 with a remainder of 2.17e-07.