Let's divide 12439 by 78
We want to divide 12439 by 78.

Going ahead to step 1:
If we divide 1 by 78, we get 0 and a remainder of 1.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 1, we end up with 1.
Bring next digit (2) of the dividend behind the 1 and repeat the process: 12 / 78

On to step 2:
When dividing 12 by 78, we get 0 with a remainder of 12.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 12 to get 12.
Append the next digit (4) from the dividend to 12 and continue with: 124 / 78

Moving on to step 3:
78 can be fit into 124 1 times, resulting in a remainder of 46.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
Subtract 78 from 124 to get 46.
Bring next digit (3) of the dividend behind the 46 and repeat the process: 463 / 78

Going ahead to step 4:
The number 78 fits into 463 5 times, leaving a remainder of 73.
Put 5 as the next digit of the answer. 
Result so far: 15.0
The remainder is 73 after subtracting 390 from 463.
Take the next digit (9) from the dividend and append it to 73, then repeat: 739 / 78

Moving on to step 5:
78 can be fit into 739 9 times, resulting in a remainder of 37.
Put 9 as the next digit of the answer. 
Result so far: 159.0
If we take 702 away from 739, we end up with 37.
Since there are no more digits in the dividend, we add a zero to the remainder making it 370, and continue the process.

Advancing to step 6:
78 can be fit into 370 4 times, resulting in a remainder of 58.
Put 4 as the next digit of the answer. 
Result so far: 159.4
Deduct 312 from 370 and we're left with 58.
Since there are no more digits in the dividend, we add a zero to the remainder making it 580, and continue the process.

Moving on to step 7:
78 goes into 580 7 times with a remainder of 34.
Put 7 as the next digit of the answer. 
Result so far: 159.47
If we take 546 away from 580, we end up with 34.
Since there are no more digits in the dividend, we add a zero to the remainder making it 340, and continue the process.

Moving on to step 8:
The number 78 fits into 340 4 times, leaving a remainder of 28.
The number 4 becomes the next digit in our result. 
Result so far: 159.474
Deduct 312 from 340 and we're left with 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

Advancing to step 9:
78 goes into 280 3 times with a remainder of 46.
Record the quotient 3 as the next digit in the result. 
Result so far: 159.4743
Deduct 234 from 280 and we're left with 46.
Since there are no more digits in the dividend, we add a zero to the remainder making it 460, and continue the process.

Let's proceed to step 10:
78 can be fit into 460 5 times, resulting in a remainder of 70.
The next digit of our result is 5. 
Result so far: 159.47435
If we subtract 390 from 460, we get 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

Going ahead to step 11:
78 goes into 700 8 times with a remainder of 76.
The next digit of our result is 8. 
Result so far: 159.474358
If we subtract 624 from 700, we get 76.
Since there are no more digits in the dividend, we add a zero to the remainder making it 760, and continue the process.

Step 12:
760 divided by 78 is 9 with a remainder of 58.
The next digit of our result is 9. 
Result so far: 159.4743589
Subtract 702 from 760 to get 58.
Since there are no more digits in the dividend, we add a zero to the remainder making it 580, and continue the process.

Going ahead to step 13:
If we divide 580 by 78, we get 7 and a remainder of 34.
Use 7 as the next digit of our solution. 
Result so far: 159.47435897
Subtracting 546 from 580 leaves us with 34.
Since there are no more digits in the dividend, we add a zero to the remainder making it 340, and continue the process.

Our division results in 159.47435897 with a remaining 3.4e-08.