Let's divide 818091 by 81
The aim is to understand the frequency of 81 in 818091.

On to step 1:
81 can be fit into 8 0 times, resulting in a remainder of 8.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 8, we get 8.
Bring next digit (1) of the dividend behind the 8 and repeat the process: 81 / 81

Moving on to step 2:
The number 81 fits into 81 1 times, leaving a remainder of 0.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Subtract 81 from 81 to get 0.
Grab the next digit (8) from the dividend, add it to 0, then carry on: 8 / 81

On to step 3:
81 can be fit into 8 0 times, resulting in a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 10.0
Subtract 0 from 8 to get 8.
Take the next digit (0) from the dividend and append it to 8, then repeat: 80 / 81

On to step 4:
When dividing 80 by 81, we get 0 with a remainder of 80.
The next digit of our result is 0. 
Result so far: 100.0
Subtract 0 from 80 to get 80.
Fetch the next digit (9) from the dividend, attach it to 80 and continue: 809 / 81

Advancing to step 5:
The number 81 fits into 809 9 times, leaving a remainder of 80.
Use 9 as the next digit of our solution. 
Result so far: 1009.0
If we take 729 away from 809, we end up with 80.
Take the next digit (1) from the dividend and append it to 80, then repeat: 801 / 81

On to step 6:
When dividing 801 by 81, we get 9 with a remainder of 72.
Put 9 as the next digit of the answer. 
Result so far: 10099.0
Deduct 729 from 801 and we're left with 72.
Since there are no more digits in the dividend, we add a zero to the remainder making it 720, and continue the process.

Going ahead to step 7:
81 goes into 720 8 times with a remainder of 72.
Record the quotient 8 as the next digit in the result. 
Result so far: 10099.8
Subtract 648 from 720 to get 72.
Since there are no more digits in the dividend, we add a zero to the remainder making it 720, and continue the process.

Advancing to step 8:
81 can be fit into 720 8 times, resulting in a remainder of 72.
Use 8 as the next digit of our solution. 
Result so far: 10099.88
The remainder is 72 after subtracting 648 from 720.
Since there are no more digits in the dividend, we add a zero to the remainder making it 720, and continue the process.

The final outcome is 10099.88, with a leftover of 0.072.