816881 ÷ 21 
We want to figure out the number of times 816881 can be divided by 21.

Step 1:
21 goes into 8 0 times with a remainder of 8.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 8, we end up with 8.
Bring next digit (1) of the dividend behind the 8 and repeat the process: 81 / 21

Step 2:
If we divide 81 by 21, we get 3 and a remainder of 18.
Put 3 as the next digit of the answer. 
Result so far: 3.0
If we take 63 away from 81, we end up with 18.
Bring next digit (6) of the dividend behind the 18 and repeat the process: 186 / 21

Moving on to step 3:
When dividing 186 by 21, we get 8 with a remainder of 18.
Write down 8 as next digit of the result. 
Result so far: 38.0
Subtract 168 from 186 to get 18.
Bring next digit (8) of the dividend behind the 18 and repeat the process: 188 / 21

Step 4:
The number 21 fits into 188 8 times, leaving a remainder of 20.
Write down 8 as next digit of the result. 
Result so far: 388.0
The remainder is 20 after subtracting 168 from 188.
Bring next digit (8) of the dividend behind the 20 and repeat the process: 208 / 21

Step 5:
If we divide 208 by 21, we get 9 and a remainder of 19.
The number 9 becomes the next digit in our result. 
Result so far: 3889.0
Subtracting 189 from 208 leaves us with 19.
Grab the next digit (1) from the dividend, add it to 19, then carry on: 191 / 21

Step 6:
The number 21 fits into 191 9 times, leaving a remainder of 2.
The number 9 becomes the next digit in our result. 
Result so far: 38899.0
Subtracting 189 from 191 leaves us with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Moving on to step 7:
If we divide 20 by 21, we get 0 and a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 38899.0
Subtracting 0 from 20 leaves us with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Let's proceed to step 8:
The number 21 fits into 200 9 times, leaving a remainder of 11.
Put 9 as the next digit of the answer. 
Result so far: 38899.09
Deduct 189 from 200 and we're left with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Let's proceed to step 9:
21 can be fit into 110 5 times, resulting in a remainder of 5.
Put 5 as the next digit of the answer. 
Result so far: 38899.095
If we take 105 away from 110, we end up with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Going ahead to step 10:
21 goes into 50 2 times with a remainder of 8.
Put 2 as the next digit of the answer. 
Result so far: 38899.0952
Subtract 42 from 50 to get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Going ahead to step 11:
21 can be fit into 80 3 times, resulting in a remainder of 17.
The number 3 becomes the next digit in our result. 
Result so far: 38899.09523
If we take 63 away from 80, we end up with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Let's proceed to step 12:
21 can be fit into 170 8 times, resulting in a remainder of 2.
Record the quotient 8 as the next digit in the result. 
Result so far: 38899.095238
The remainder is 2 after subtracting 168 from 170.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

On to step 13:
21 goes into 20 0 times with a remainder of 20.
Write down 0 as next digit of the result. 
Result so far: 38899.095238
Subtracting 0 from 20 leaves us with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Going ahead to step 14:
The number 21 fits into 200 9 times, leaving a remainder of 11.
Put 9 as the next digit of the answer. 
Result so far: 38899.09523809
Deduct 189 from 200 and we're left with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

The final outcome is 38899.09523809, with a leftover of 1.1e-08.