816891 ÷ 21 
Let's see how many times 21 fits into 816891.

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
Deduct 0 from 8 and we're left with 8.
Append the next digit (1) from the dividend to 8 and continue with: 81 / 21

Moving on to step 2:
21 can be fit into 81 3 times, resulting in a remainder of 18.
Use 3 as the next digit of our solution. 
Result so far: 3.0
Subtracting 63 from 81 leaves us with 18.
Grab the next digit (6) from the dividend, add it to 18, then carry on: 186 / 21

Going ahead to step 3:
The number 21 fits into 186 8 times, leaving a remainder of 18.
Put 8 as the next digit of the answer. 
Result so far: 38.0
Deduct 168 from 186 and we're left with 18.
Fetch the next digit (8) from the dividend, attach it to 18 and continue: 188 / 21

Moving on to step 4:
When dividing 188 by 21, we get 8 with a remainder of 20.
Use 8 as the next digit of our solution. 
Result so far: 388.0
Subtracting 168 from 188 leaves us with 20.
Bring next digit (9) of the dividend behind the 20 and repeat the process: 209 / 21

On to step 5:
21 can be fit into 209 9 times, resulting in a remainder of 20.
Put 9 as the next digit of the answer. 
Result so far: 3889.0
If we take 189 away from 209, we end up with 20.
Bring next digit (1) of the dividend behind the 20 and repeat the process: 201 / 21

On to step 6:
If we divide 201 by 21, we get 9 and a remainder of 12.
Write down 9 as next digit of the result. 
Result so far: 38899.0
The remainder is 12 after subtracting 189 from 201.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Moving on to step 7:
The number 21 fits into 120 5 times, leaving a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 38899.5
Subtract 105 from 120 to get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Moving on to step 8:
150 divided by 21 is 7 with a remainder of 3.
Write down 7 as next digit of the result. 
Result so far: 38899.57
Subtracting 147 from 150 leaves us with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Step 9:
When dividing 30 by 21, we get 1 with a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 38899.571
If we subtract 21 from 30, we get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Moving on to step 10:
If we divide 90 by 21, we get 4 and a remainder of 6.
Put 4 as the next digit of the answer. 
Result so far: 38899.5714
Deduct 84 from 90 and we're left 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.

Going ahead to step 11:
The number 21 fits into 60 2 times, leaving a remainder of 18.
Put 2 as the next digit of the answer. 
Result so far: 38899.57142
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.

Advancing to step 12:
180 divided by 21 is 8 with a remainder of 12.
The next digit of our result is 8. 
Result so far: 38899.571428
Subtract 168 from 180 to get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Going ahead to step 13:
When dividing 120 by 21, we get 5 with a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 38899.5714285
If we take 105 away from 120, we end up 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.

Advancing to step 14:
21 can be fit into 150 7 times, resulting in a remainder of 3.
Write down 7 as next digit of the result. 
Result so far: 38899.57142857
The remainder is 3 after subtracting 147 from 150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

The quotient of the division is 38899.57142857, and the remainder is 3e-09.