850686 ÷ 21 
Our goal is to divide 850686 by 21.

On to step 1:
8 divided by 21 is 0 with a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 8 after subtracting 0 from 8.
Append the next digit (5) from the dividend to 8 and continue with: 85 / 21

Going ahead to step 2:
85 divided by 21 is 4 with a remainder of 1.
The number 4 becomes the next digit in our result. 
Result so far: 4.0
The remainder is 1 after subtracting 84 from 85.
Bring next digit (0) of the dividend behind the 1 and repeat the process: 10 / 21

Moving on to step 3:
When dividing 10 by 21, we get 0 with a remainder of 10.
Use 0 as the next digit of our solution. 
Result so far: 40.0
If we subtract 0 from 10, we get 10.
Append the next digit (6) from the dividend to 10 and continue with: 106 / 21

Step 4:
When dividing 106 by 21, we get 5 with a remainder of 1.
The next digit of our result is 5. 
Result so far: 405.0
Deduct 105 from 106 and we're left with 1.
Append the next digit (8) from the dividend to 1 and continue with: 18 / 21

Let's proceed to step 5:
The number 21 fits into 18 0 times, leaving a remainder of 18.
The number 0 becomes the next digit in our result. 
Result so far: 4050.0
If we take 0 away from 18, we end up with 18.
Include the next digit (6) from the dividend after 18, then repeat: 186 / 21

Step 6:
The number 21 fits into 186 8 times, leaving a remainder of 18.
Use 8 as the next digit of our solution. 
Result so far: 40508.0
Subtracting 168 from 186 leaves us with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Let's proceed to step 7:
The number 21 fits into 180 8 times, leaving a remainder of 12.
Put 8 as the next digit of the answer. 
Result so far: 40508.8
Deduct 168 from 180 and we're left with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Step 8:
When dividing 120 by 21, we get 5 with a remainder of 15.
Record the quotient 5 as the next digit in the result. 
Result so far: 40508.85
Subtracting 105 from 120 leaves us with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Going ahead to step 9:
When dividing 150 by 21, we get 7 with a remainder of 3.
Use 7 as the next digit of our solution. 
Result so far: 40508.857
Subtract 147 from 150 to get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Advancing to step 10:
When dividing 30 by 21, we get 1 with a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 40508.8571
If we take 21 away from 30, we end up with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Going ahead to step 11:
21 goes into 90 4 times with a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 40508.85714
Subtracting 84 from 90 leaves us with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Step 12:
If we divide 60 by 21, we get 2 and a remainder of 18.
Put 2 as the next digit of the answer. 
Result so far: 40508.857142
If we take 42 away from 60, we end up with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Step 13:
21 goes into 180 8 times with a remainder of 12.
Record the quotient 8 as the next digit in the result. 
Result so far: 40508.8571428
If we take 168 away from 180, we end up with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Advancing to step 14:
120 divided by 21 is 5 with a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 40508.85714285
Deduct 105 from 120 and we're left with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

The final outcome is 40508.85714285, with a leftover of 1.5e-08.