We look at the division of 643720 by 81 
We want to figure out the number of times 643720 can be divided by 81.

Advancing to step 1:
If we divide 6 by 81, we get 0 and a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Bring next digit (4) of the dividend behind the 6 and repeat the process: 64 / 81

Let's proceed to step 2:
64 divided by 81 is 0 with a remainder of 64.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 64 and we're left with 64.
Fetch the next digit (3) from the dividend, attach it to 64 and continue: 643 / 81

Moving on to step 3:
When dividing 643 by 81, we get 7 with a remainder of 76.
Record the quotient 7 as the next digit in the result. 
Result so far: 7.0
If we subtract 567 from 643, we get 76.
Bring next digit (7) of the dividend behind the 76 and repeat the process: 767 / 81

Step 4:
If we divide 767 by 81, we get 9 and a remainder of 38.
Write down 9 as next digit of the result. 
Result so far: 79.0
If we take 729 away from 767, we end up with 38.
Include the next digit (2) from the dividend after 38, then repeat: 382 / 81

Advancing to step 5:
When dividing 382 by 81, we get 4 with a remainder of 58.
Write down 4 as next digit of the result. 
Result so far: 794.0
If we subtract 324 from 382, we get 58.
Take the next digit (0) from the dividend and append it to 58, then repeat: 580 / 81

Step 6:
When dividing 580 by 81, we get 7 with a remainder of 13.
Use 7 as the next digit of our solution. 
Result so far: 7947.0
Subtracting 567 from 580 leaves us with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Going ahead to step 7:
130 divided by 81 is 1 with a remainder of 49.
Record the quotient 1 as the next digit in the result. 
Result so far: 7947.1
The remainder is 49 after subtracting 81 from 130.
Since there are no more digits in the dividend, we add a zero to the remainder making it 490, and continue the process.

Going ahead to step 8:
81 can be fit into 490 6 times, resulting in a remainder of 4.
Record the quotient 6 as the next digit in the result. 
Result so far: 7947.16
If we subtract 486 from 490, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Let's proceed to step 9:
81 goes into 40 0 times with a remainder of 40.
The number 0 becomes the next digit in our result. 
Result so far: 7947.16
If we subtract 0 from 40, we get 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Let's proceed to step 10:
81 can be fit into 400 4 times, resulting in a remainder of 76.
Use 4 as the next digit of our solution. 
Result so far: 7947.1604
Subtracting 324 from 400 leaves us with 76.
Since there are no more digits in the dividend, we add a zero to the remainder making it 760, and continue the process.

Step 11:
760 divided by 81 is 9 with a remainder of 31.
Put 9 as the next digit of the answer. 
Result so far: 7947.16049
If we take 729 away from 760, we end up with 31.
Since there are no more digits in the dividend, we add a zero to the remainder making it 310, and continue the process.

Moving on to step 12:
If we divide 310 by 81, we get 3 and a remainder of 67.
Put 3 as the next digit of the answer. 
Result so far: 7947.160493
The remainder is 67 after subtracting 243 from 310.
Since there are no more digits in the dividend, we add a zero to the remainder making it 670, and continue the process.

On to step 13:
81 goes into 670 8 times with a remainder of 22.
The number 8 becomes the next digit in our result. 
Result so far: 7947.1604938
Deduct 648 from 670 and we're left with 22.
Since there are no more digits in the dividend, we add a zero to the remainder making it 220, and continue the process.

Let's proceed to step 14:
81 can be fit into 220 2 times, resulting in a remainder of 58.
The next digit of our result is 2. 
Result so far: 7947.16049382
Deduct 162 from 220 and we're left with 58.
Since there are no more digits in the dividend, we add a zero to the remainder making it 580, and continue the process.

The final result is 7947.16049382 with a remainder of 5.8e-08.