We look at the division of 260299 by 81 
The aim is to understand the frequency of 81 in 260299.

On to step 1:
When dividing 2 by 81, we get 0 with a remainder of 2.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 2 leaves us with 2.
Bring next digit (6) of the dividend behind the 2 and repeat the process: 26 / 81

Step 2:
When dividing 26 by 81, we get 0 with a remainder of 26.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 26 to get 26.
Grab the next digit (0) from the dividend, add it to 26, then carry on: 260 / 81

Step 3:
If we divide 260 by 81, we get 3 and a remainder of 17.
Record the quotient 3 as the next digit in the result. 
Result so far: 3.0
The remainder is 17 after subtracting 243 from 260.
Grab the next digit (2) from the dividend, add it to 17, then carry on: 172 / 81

On to step 4:
172 divided by 81 is 2 with a remainder of 10.
Write down 2 as next digit of the result. 
Result so far: 32.0
If we subtract 162 from 172, we get 10.
Bring next digit (9) of the dividend behind the 10 and repeat the process: 109 / 81

Advancing to step 5:
81 can be fit into 109 1 times, resulting in a remainder of 28.
The next digit of our result is 1. 
Result so far: 321.0
If we subtract 81 from 109, we get 28.
Include the next digit (9) from the dividend after 28, then repeat: 289 / 81

On to step 6:
If we divide 289 by 81, we get 3 and a remainder of 46.
Write down 3 as next digit of the result. 
Result so far: 3213.0
If we take 243 away from 289, we end up with 46.
Since there are no more digits in the dividend, we add a zero to the remainder making it 460, and continue the process.

Step 7:
81 goes into 460 5 times with a remainder of 55.
Put 5 as the next digit of the answer. 
Result so far: 3213.5
The remainder is 55 after subtracting 405 from 460.
Since there are no more digits in the dividend, we add a zero to the remainder making it 550, and continue the process.

On to step 8:
The number 81 fits into 550 6 times, leaving a remainder of 64.
Use 6 as the next digit of our solution. 
Result so far: 3213.56
Deduct 486 from 550 and we're left with 64.
Since there are no more digits in the dividend, we add a zero to the remainder making it 640, and continue the process.

Moving on to step 9:
640 divided by 81 is 7 with a remainder of 73.
Record the quotient 7 as the next digit in the result. 
Result so far: 3213.567
If we take 567 away from 640, we end up with 73.
Since there are no more digits in the dividend, we add a zero to the remainder making it 730, and continue the process.

Let's proceed to step 10:
81 can be fit into 730 9 times, resulting in a remainder of 1.
The next digit of our result is 9. 
Result so far: 3213.5679
The remainder is 1 after subtracting 729 from 730.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

On to step 11:
81 goes into 10 0 times with a remainder of 10.
The number 0 becomes the next digit in our result. 
Result so far: 3213.5679
The remainder is 10 after subtracting 0 from 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Advancing to step 12:
If we divide 100 by 81, we get 1 and a remainder of 19.
Write down 1 as next digit of the result. 
Result so far: 3213.567901
Subtracting 81 from 100 leaves us with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Advancing to step 13:
81 can be fit into 190 2 times, resulting in a remainder of 28.
Use 2 as the next digit of our solution. 
Result so far: 3213.5679012
The remainder is 28 after subtracting 162 from 190.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

Step 14:
81 goes into 280 3 times with a remainder of 37.
The number 3 becomes the next digit in our result. 
Result so far: 3213.56790123
The remainder is 37 after subtracting 243 from 280.
Since there are no more digits in the dividend, we add a zero to the remainder making it 370, and continue the process.

The final result is 3213.56790123 with a remainder of 3.7e-08.