8519721 ÷ 857 
Our goal is to divide 8519721 by 857.

Step 1:
857 goes into 8 0 times with a remainder of 8.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 8 to get 8.
Bring next digit (5) of the dividend behind the 8 and repeat the process: 85 / 857

Going ahead to step 2:
857 can be fit into 85 0 times, resulting in a remainder of 85.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 85, we end up with 85.
Include the next digit (1) from the dividend after 85, then repeat: 851 / 857

Going ahead to step 3:
When dividing 851 by 857, we get 0 with a remainder of 851.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 851 and we're left with 851.
Append the next digit (9) from the dividend to 851 and continue with: 8519 / 857

Moving on to step 4:
857 can be fit into 8519 9 times, resulting in a remainder of 806.
The next digit of our result is 9. 
Result so far: 9.0
If we subtract 7713 from 8519, we get 806.
Grab the next digit (7) from the dividend, add it to 806, then carry on: 8067 / 857

Let's proceed to step 5:
857 can be fit into 8067 9 times, resulting in a remainder of 354.
Record the quotient 9 as the next digit in the result. 
Result so far: 99.0
Subtract 7713 from 8067 to get 354.
Include the next digit (2) from the dividend after 354, then repeat: 3542 / 857

Let's proceed to step 6:
857 can be fit into 3542 4 times, resulting in a remainder of 114.
The number 4 becomes the next digit in our result. 
Result so far: 994.0
If we take 3428 away from 3542, we end up with 114.
Include the next digit (1) from the dividend after 114, then repeat: 1141 / 857

Going ahead to step 7:
1141 divided by 857 is 1 with a remainder of 284.
Write down 1 as next digit of the result. 
Result so far: 9941.0
If we subtract 857 from 1141, we get 284.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2840, and continue the process.

On to step 8:
If we divide 2840 by 857, we get 3 and a remainder of 269.
Put 3 as the next digit of the answer. 
Result so far: 9941.3
The remainder is 269 after subtracting 2571 from 2840.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2690, and continue the process.

On to step 9:
The number 857 fits into 2690 3 times, leaving a remainder of 119.
The next digit of our result is 3. 
Result so far: 9941.33
Deduct 2571 from 2690 and we're left with 119.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1190, and continue the process.

The final outcome is 9941.33, with a leftover of 0.119.