861266 ÷ 21 
Let's see how many times 21 fits into 861266.

Let's proceed to step 1:
21 goes into 8 0 times with a remainder of 8.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 8 leaves us with 8.
Bring next digit (6) of the dividend behind the 8 and repeat the process: 86 / 21

Moving on to step 2:
When dividing 86 by 21, we get 4 with a remainder of 2.
Write down 4 as next digit of the result. 
Result so far: 4.0
Subtracting 84 from 86 leaves us with 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 21

On to step 3:
21 can be fit into 21 1 times, resulting in a remainder of 0.
Put 1 as the next digit of the answer. 
Result so far: 41.0
Subtracting 21 from 21 leaves us with 0.
Take the next digit (2) from the dividend and append it to 0, then repeat: 2 / 21

Let's proceed to step 4:
If we divide 2 by 21, we get 0 and a remainder of 2.
Record the quotient 0 as the next digit in the result. 
Result so far: 410.0
If we subtract 0 from 2, we get 2.
Append the next digit (6) from the dividend to 2 and continue with: 26 / 21

Moving on to step 5:
21 can be fit into 26 1 times, resulting in a remainder of 5.
Record the quotient 1 as the next digit in the result. 
Result so far: 4101.0
Subtracting 21 from 26 leaves us with 5.
Bring next digit (6) of the dividend behind the 5 and repeat the process: 56 / 21

Moving on to step 6:
56 divided by 21 is 2 with a remainder of 14.
Use 2 as the next digit of our solution. 
Result so far: 41012.0
Deduct 42 from 56 and we're left with 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Going ahead to step 7:
If we divide 140 by 21, we get 6 and a remainder of 14.
The number 6 becomes the next digit in our result. 
Result so far: 41012.6
If we subtract 126 from 140, we get 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Moving on to step 8:
The number 21 fits into 140 6 times, leaving a remainder of 14.
The next digit of our result is 6. 
Result so far: 41012.66
Subtracting 126 from 140 leaves us with 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

The final result is 41012.66 with a remainder of 0.014.