12398656 ÷ 604 
Our goal is to divide 12398656 by 604.

On to step 1:
If we divide 1 by 604, we get 0 and a remainder of 1.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 1 leaves us with 1.
Grab the next digit (2) from the dividend, add it to 1, then carry on: 12 / 604

On to step 2:
604 goes into 12 0 times with a remainder of 12.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 12 leaves us with 12.
Include the next digit (3) from the dividend after 12, then repeat: 123 / 604

Advancing to step 3:
123 divided by 604 is 0 with a remainder of 123.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 123, we end up with 123.
Append the next digit (9) from the dividend to 123 and continue with: 1239 / 604

Advancing to step 4:
When dividing 1239 by 604, we get 2 with a remainder of 31.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
Subtract 1208 from 1239 to get 31.
Append the next digit (8) from the dividend to 31 and continue with: 318 / 604

Moving on to step 5:
When dividing 318 by 604, we get 0 with a remainder of 318.
Use 0 as the next digit of our solution. 
Result so far: 20.0
Subtracting 0 from 318 leaves us with 318.
Fetch the next digit (6) from the dividend, attach it to 318 and continue: 3186 / 604

Step 6:
The number 604 fits into 3186 5 times, leaving a remainder of 166.
Use 5 as the next digit of our solution. 
Result so far: 205.0
If we take 3020 away from 3186, we end up with 166.
Grab the next digit (5) from the dividend, add it to 166, then carry on: 1665 / 604

Advancing to step 7:
604 can be fit into 1665 2 times, resulting in a remainder of 457.
Record the quotient 2 as the next digit in the result. 
Result so far: 2052.0
Deduct 1208 from 1665 and we're left with 457.
Bring next digit (6) of the dividend behind the 457 and repeat the process: 4576 / 604

Step 8:
4576 divided by 604 is 7 with a remainder of 348.
Put 7 as the next digit of the answer. 
Result so far: 20527.0
If we subtract 4228 from 4576, we get 348.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3480, and continue the process.

On to step 9:
The number 604 fits into 3480 5 times, leaving a remainder of 460.
Write down 5 as next digit of the result. 
Result so far: 20527.5
If we take 3020 away from 3480, we end up with 460.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4600, and continue the process.

Going ahead to step 10:
If we divide 4600 by 604, we get 7 and a remainder of 372.
Record the quotient 7 as the next digit in the result. 
Result so far: 20527.57
The remainder is 372 after subtracting 4228 from 4600.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3720, and continue the process.

Advancing to step 11:
604 goes into 3720 6 times with a remainder of 96.
Use 6 as the next digit of our solution. 
Result so far: 20527.576
Subtract 3624 from 3720 to get 96.
Since there are no more digits in the dividend, we add a zero to the remainder making it 960, and continue the process.

On to step 12:
960 divided by 604 is 1 with a remainder of 356.
The number 1 becomes the next digit in our result. 
Result so far: 20527.5761
Subtracting 604 from 960 leaves us with 356.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3560, and continue the process.

Going ahead to step 13:
3560 divided by 604 is 5 with a remainder of 540.
Put 5 as the next digit of the answer. 
Result so far: 20527.57615
If we take 3020 away from 3560, we end up with 540.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5400, and continue the process.

Step 14:
When dividing 5400 by 604, we get 8 with a remainder of 568.
Record the quotient 8 as the next digit in the result. 
Result so far: 20527.576158
If we subtract 4832 from 5400, we get 568.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5680, and continue the process.

On to step 15:
The number 604 fits into 5680 9 times, leaving a remainder of 244.
Record the quotient 9 as the next digit in the result. 
Result so far: 20527.5761589
Subtract 5436 from 5680 to get 244.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2440, and continue the process.

Advancing to step 16:
2440 divided by 604 is 4 with a remainder of 24.
Record the quotient 4 as the next digit in the result. 
Result so far: 20527.57615894
Deduct 2416 from 2440 and we're left 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 20527.57615894, with a leftover of 2.4e-08.