We're dividing 351221 by 78 
Our goal is to divide 351221 by 78.

Going ahead to step 1:
78 can be fit into 3 0 times, resulting in a remainder of 3.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 3 to get 3.
Include the next digit (5) from the dividend after 3, then repeat: 35 / 78

Going ahead to step 2:
If we divide 35 by 78, we get 0 and a remainder of 35.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 35 leaves us with 35.
Include the next digit (1) from the dividend after 35, then repeat: 351 / 78

Advancing to step 3:
78 goes into 351 4 times with a remainder of 39.
Record the quotient 4 as the next digit in the result. 
Result so far: 4.0
The remainder is 39 after subtracting 312 from 351.
Include the next digit (2) from the dividend after 39, then repeat: 392 / 78

Going ahead to step 4:
78 can be fit into 392 5 times, resulting in a remainder of 2.
Use 5 as the next digit of our solution. 
Result so far: 45.0
If we take 390 away from 392, we end up with 2.
Append the next digit (2) from the dividend to 2 and continue with: 22 / 78

On to step 5:
The number 78 fits into 22 0 times, leaving a remainder of 22.
Use 0 as the next digit of our solution. 
Result so far: 450.0
If we subtract 0 from 22, we get 22.
Fetch the next digit (1) from the dividend, attach it to 22 and continue: 221 / 78

Step 6:
221 divided by 78 is 2 with a remainder of 65.
Put 2 as the next digit of the answer. 
Result so far: 4502.0
The remainder is 65 after subtracting 156 from 221.
Since there are no more digits in the dividend, we add a zero to the remainder making it 650, and continue the process.

Going ahead to step 7:
650 divided by 78 is 8 with a remainder of 26.
Write down 8 as next digit of the result. 
Result so far: 4502.8
If we subtract 624 from 650, we get 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

Step 8:
The number 78 fits into 260 3 times, leaving a remainder of 26.
Put 3 as the next digit of the answer. 
Result so far: 4502.83
Deduct 234 from 260 and we're left with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

Advancing to step 9:
The number 78 fits into 260 3 times, leaving a remainder of 26.
Write down 3 as next digit of the result. 
Result so far: 4502.833
Subtracting 234 from 260 leaves us with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

The final result is 4502.833 with a remainder of 0.0026.