We look at the division of 635342 by 81 
The aim is to understand the frequency of 81 in 635342.

Let's proceed to step 1:
If we divide 6 by 81, we get 0 and a remainder of 6.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Append the next digit (3) from the dividend to 6 and continue with: 63 / 81

Let's proceed to step 2:
If we divide 63 by 81, we get 0 and a remainder of 63.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we subtract 0 from 63, we get 63.
Grab the next digit (5) from the dividend, add it to 63, then carry on: 635 / 81

Moving on to step 3:
81 goes into 635 7 times with a remainder of 68.
Record the quotient 7 as the next digit in the result. 
Result so far: 7.0
Subtract 567 from 635 to get 68.
Grab the next digit (3) from the dividend, add it to 68, then carry on: 683 / 81

Moving on to step 4:
81 goes into 683 8 times with a remainder of 35.
The next digit of our result is 8. 
Result so far: 78.0
Subtract 648 from 683 to get 35.
Bring next digit (4) of the dividend behind the 35 and repeat the process: 354 / 81

On to step 5:
When dividing 354 by 81, we get 4 with a remainder of 30.
The number 4 becomes the next digit in our result. 
Result so far: 784.0
If we subtract 324 from 354, we get 30.
Take the next digit (2) from the dividend and append it to 30, then repeat: 302 / 81

Step 6:
The number 81 fits into 302 3 times, leaving a remainder of 59.
The number 3 becomes the next digit in our result. 
Result so far: 7843.0
Subtracting 243 from 302 leaves us with 59.
Since there are no more digits in the dividend, we add a zero to the remainder making it 590, and continue the process.

Step 7:
81 goes into 590 7 times with a remainder of 23.
Record the quotient 7 as the next digit in the result. 
Result so far: 7843.7
Deduct 567 from 590 and we're left with 23.
Since there are no more digits in the dividend, we add a zero to the remainder making it 230, and continue the process.

Step 8:
If we divide 230 by 81, we get 2 and a remainder of 68.
Write down 2 as next digit of the result. 
Result so far: 7843.72
If we take 162 away from 230, we end up with 68.
Since there are no more digits in the dividend, we add a zero to the remainder making it 680, and continue the process.

Step 9:
If we divide 680 by 81, we get 8 and a remainder of 32.
Use 8 as the next digit of our solution. 
Result so far: 7843.728
If we take 648 away from 680, we end up with 32.
Since there are no more digits in the dividend, we add a zero to the remainder making it 320, and continue the process.

Let's proceed to step 10:
When dividing 320 by 81, we get 3 with a remainder of 77.
Write down 3 as next digit of the result. 
Result so far: 7843.7283
The remainder is 77 after subtracting 243 from 320.
Since there are no more digits in the dividend, we add a zero to the remainder making it 770, and continue the process.

Let's proceed to step 11:
81 can be fit into 770 9 times, resulting in a remainder of 41.
The next digit of our result is 9. 
Result so far: 7843.72839
The remainder is 41 after subtracting 729 from 770.
Since there are no more digits in the dividend, we add a zero to the remainder making it 410, and continue the process.

Step 12:
410 divided by 81 is 5 with a remainder of 5.
Write down 5 as next digit of the result. 
Result so far: 7843.728395
Subtract 405 from 410 to get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

On to step 13:
50 divided by 81 is 0 with a remainder of 50.
Put 0 as the next digit of the answer. 
Result so far: 7843.728395
Subtract 0 from 50 to get 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

Moving on to step 14:
500 divided by 81 is 6 with a remainder of 14.
Write down 6 as next digit of the result. 
Result so far: 7843.72839506
Subtracting 486 from 500 leaves us with 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

The final result is 7843.72839506 with a remainder of 1.4e-08.