91728521 divided by 81 
We want to figure out the number of times 91728521 can be divided by 81.

Going ahead to step 1:
When dividing 9 by 81, we get 0 with a remainder of 9.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 9 to get 9.
Include the next digit (1) from the dividend after 9, then repeat: 91 / 81

Let's proceed to step 2:
81 goes into 91 1 times with a remainder of 10.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
If we subtract 81 from 91, we get 10.
Fetch the next digit (7) from the dividend, attach it to 10 and continue: 107 / 81

On to step 3:
81 can be fit into 107 1 times, resulting in a remainder of 26.
Use 1 as the next digit of our solution. 
Result so far: 11.0
Deduct 81 from 107 and we're left with 26.
Grab the next digit (2) from the dividend, add it to 26, then carry on: 262 / 81

Let's proceed to step 4:
262 divided by 81 is 3 with a remainder of 19.
Write down 3 as next digit of the result. 
Result so far: 113.0
Subtracting 243 from 262 leaves us with 19.
Take the next digit (8) from the dividend and append it to 19, then repeat: 198 / 81

On to step 5:
198 divided by 81 is 2 with a remainder of 36.
Put 2 as the next digit of the answer. 
Result so far: 1132.0
Subtract 162 from 198 to get 36.
Append the next digit (5) from the dividend to 36 and continue with: 365 / 81

Moving on to step 6:
81 can be fit into 365 4 times, resulting in a remainder of 41.
Use 4 as the next digit of our solution. 
Result so far: 11324.0
Subtract 324 from 365 to get 41.
Take the next digit (2) from the dividend and append it to 41, then repeat: 412 / 81

Step 7:
If we divide 412 by 81, we get 5 and a remainder of 7.
Use 5 as the next digit of our solution. 
Result so far: 113245.0
The remainder is 7 after subtracting 405 from 412.
Grab the next digit (1) from the dividend, add it to 7, then carry on: 71 / 81

Moving on to step 8:
The number 81 fits into 71 0 times, leaving a remainder of 71.
The next digit of our result is 0. 
Result so far: 1132450.0
Subtract 0 from 71 to get 71.
Since there are no more digits in the dividend, we add a zero to the remainder making it 710, and continue the process.

Advancing to step 9:
710 divided by 81 is 8 with a remainder of 62.
Record the quotient 8 as the next digit in the result. 
Result so far: 1132450.8
The remainder is 62 after subtracting 648 from 710.
Since there are no more digits in the dividend, we add a zero to the remainder making it 620, and continue the process.

On to step 10:
81 can be fit into 620 7 times, resulting in a remainder of 53.
Put 7 as the next digit of the answer. 
Result so far: 1132450.87
If we subtract 567 from 620, we get 53.
Since there are no more digits in the dividend, we add a zero to the remainder making it 530, and continue the process.

Step 11:
81 goes into 530 6 times with a remainder of 44.
Write down 6 as next digit of the result. 
Result so far: 1132450.876
If we subtract 486 from 530, we get 44.
Since there are no more digits in the dividend, we add a zero to the remainder making it 440, and continue the process.

Step 12:
If we divide 440 by 81, we get 5 and a remainder of 35.
The number 5 becomes the next digit in our result. 
Result so far: 1132450.8765
If we subtract 405 from 440, we get 35.
Since there are no more digits in the dividend, we add a zero to the remainder making it 350, and continue the process.

Going ahead to step 13:
81 can be fit into 350 4 times, resulting in a remainder of 26.
Write down 4 as next digit of the result. 
Result so far: 1132450.87654
Deduct 324 from 350 and we're left with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

Step 14:
If we divide 260 by 81, we get 3 and a remainder of 17.
Put 3 as the next digit of the answer. 
Result so far: 1132450.876543
The remainder is 17 after subtracting 243 from 260.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

On to step 15:
The number 81 fits into 170 2 times, leaving a remainder of 8.
The number 2 becomes the next digit in our result. 
Result so far: 1132450.8765432
If we subtract 162 from 170, we 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 16:
81 goes into 80 0 times with a remainder of 80.
Record the quotient 0 as the next digit in the result. 
Result so far: 1132450.8765432
If we subtract 0 from 80, we get 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

The final result is 1132450.8765432 with a remainder of 8e-08.