We look at the division of 830475 by 81 
The aim is to understand the frequency of 81 in 830475.

On to step 1:
If we divide 8 by 81, we get 0 and a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 8 to get 8.
Include the next digit (3) from the dividend after 8, then repeat: 83 / 81

Advancing to step 2:
If we divide 83 by 81, we get 1 and a remainder of 2.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Deduct 81 from 83 and we're left with 2.
Include the next digit (0) from the dividend after 2, then repeat: 20 / 81

On to step 3:
20 divided by 81 is 0 with a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 10.0
If we subtract 0 from 20, we get 20.
Bring next digit (4) of the dividend behind the 20 and repeat the process: 204 / 81

On to step 4:
81 goes into 204 2 times with a remainder of 42.
The next digit of our result is 2. 
Result so far: 102.0
The remainder is 42 after subtracting 162 from 204.
Include the next digit (7) from the dividend after 42, then repeat: 427 / 81

Advancing to step 5:
81 goes into 427 5 times with a remainder of 22.
Put 5 as the next digit of the answer. 
Result so far: 1025.0
Subtract 405 from 427 to get 22.
Fetch the next digit (5) from the dividend, attach it to 22 and continue: 225 / 81

On to step 6:
225 divided by 81 is 2 with a remainder of 63.
The number 2 becomes the next digit in our result. 
Result so far: 10252.0
Subtracting 162 from 225 leaves us with 63.
Since there are no more digits in the dividend, we add a zero to the remainder making it 630, and continue the process.

On to step 7:
81 can be fit into 630 7 times, resulting in a remainder of 63.
The number 7 becomes the next digit in our result. 
Result so far: 10252.7
The remainder is 63 after subtracting 567 from 630.
Since there are no more digits in the dividend, we add a zero to the remainder making it 630, and continue the process.

On to step 8:
The number 81 fits into 630 7 times, leaving a remainder of 63.
Write down 7 as next digit of the result. 
Result so far: 10252.77
If we subtract 567 from 630, we get 63.
Since there are no more digits in the dividend, we add a zero to the remainder making it 630, and continue the process.

The final result is 10252.77 with a remainder of 0.063.