We divide 813543 by 21
We want to figure out the number of times 813543 can be divided by 21.

Moving on to step 1:
8 divided by 21 is 0 with a remainder of 8.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 8, we get 8.
Fetch the next digit (1) from the dividend, attach it to 8 and continue: 81 / 21

Advancing to step 2:
21 goes into 81 3 times with a remainder of 18.
Use 3 as the next digit of our solution. 
Result so far: 3.0
If we take 63 away from 81, we end up with 18.
Bring next digit (3) of the dividend behind the 18 and repeat the process: 183 / 21

Step 3:
If we divide 183 by 21, we get 8 and a remainder of 15.
The next digit of our result is 8. 
Result so far: 38.0
Deduct 168 from 183 and we're left with 15.
Fetch the next digit (5) from the dividend, attach it to 15 and continue: 155 / 21

On to step 4:
21 can be fit into 155 7 times, resulting in a remainder of 8.
Write down 7 as next digit of the result. 
Result so far: 387.0
If we take 147 away from 155, we end up with 8.
Fetch the next digit (4) from the dividend, attach it to 8 and continue: 84 / 21

Going ahead to step 5:
If we divide 84 by 21, we get 4 and a remainder of 0.
Put 4 as the next digit of the answer. 
Result so far: 3874.0
Subtract 84 from 84 to get 0.
Append the next digit (3) from the dividend to 0 and continue with: 3 / 21

Let's proceed to step 6:
21 can be fit into 3 0 times, resulting in a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 38740.0
Subtract 0 from 3 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.

On to step 7:
21 goes into 30 1 times with a remainder of 9.
Record the quotient 1 as the next digit in the result. 
Result so far: 38740.1
The remainder is 9 after subtracting 21 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Step 8:
When dividing 90 by 21, we get 4 with a remainder of 6.
Use 4 as the next digit of our solution. 
Result so far: 38740.14
If we subtract 84 from 90, we get 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 9:
21 can be fit into 60 2 times, resulting in a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 38740.142
Subtract 42 from 60 to get 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Moving on to step 10:
21 goes into 180 8 times with a remainder of 12.
The next digit of our result is 8. 
Result so far: 38740.1428
The remainder is 12 after subtracting 168 from 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Step 11:
When dividing 120 by 21, we get 5 with a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 38740.14285
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.

On to step 12:
When dividing 150 by 21, we get 7 with a remainder of 3.
Write down 7 as next digit of the result. 
Result so far: 38740.142857
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.

Going ahead to step 13:
21 goes into 30 1 times with a remainder of 9.
The next digit of our result is 1. 
Result so far: 38740.1428571
The remainder is 9 after subtracting 21 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Advancing to step 14:
90 divided by 21 is 4 with a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 38740.14285714
The remainder is 6 after subtracting 84 from 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

The final outcome is 38740.14285714, with a leftover of 6e-09.