We look at the division of 523210 by 81 
The aim is to understand the frequency of 81 in 523210.

Step 1:
If we divide 5 by 81, we get 0 and a remainder of 5.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 5 to get 5.
Include the next digit (2) from the dividend after 5, then repeat: 52 / 81

On to step 2:
If we divide 52 by 81, we get 0 and a remainder of 52.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 52 leaves us with 52.
Bring next digit (3) of the dividend behind the 52 and repeat the process: 523 / 81

On to step 3:
The number 81 fits into 523 6 times, leaving a remainder of 37.
Use 6 as the next digit of our solution. 
Result so far: 6.0
Subtract 486 from 523 to get 37.
Fetch the next digit (2) from the dividend, attach it to 37 and continue: 372 / 81

Step 4:
If we divide 372 by 81, we get 4 and a remainder of 48.
Record the quotient 4 as the next digit in the result. 
Result so far: 64.0
If we subtract 324 from 372, we get 48.
Grab the next digit (1) from the dividend, add it to 48, then carry on: 481 / 81

Going ahead to step 5:
The number 81 fits into 481 5 times, leaving a remainder of 76.
Put 5 as the next digit of the answer. 
Result so far: 645.0
If we take 405 away from 481, we end up with 76.
Bring next digit (0) of the dividend behind the 76 and repeat the process: 760 / 81

On to step 6:
81 can be fit into 760 9 times, resulting in a remainder of 31.
Write down 9 as next digit of the result. 
Result so far: 6459.0
The remainder is 31 after subtracting 729 from 760.
Since there are no more digits in the dividend, we add a zero to the remainder making it 310, and continue the process.

Moving on to step 7:
The number 81 fits into 310 3 times, leaving a remainder of 67.
Write down 3 as next digit of the result. 
Result so far: 6459.3
If we take 243 away from 310, we end up with 67.
Since there are no more digits in the dividend, we add a zero to the remainder making it 670, and continue the process.

Let's proceed to step 8:
When dividing 670 by 81, we get 8 with a remainder of 22.
The number 8 becomes the next digit in our result. 
Result so far: 6459.38
If we subtract 648 from 670, we get 22.
Since there are no more digits in the dividend, we add a zero to the remainder making it 220, and continue the process.

Advancing to step 9:
The number 81 fits into 220 2 times, leaving a remainder of 58.
The number 2 becomes the next digit in our result. 
Result so far: 6459.382
Subtract 162 from 220 to get 58.
Since there are no more digits in the dividend, we add a zero to the remainder making it 580, and continue the process.

Going ahead to step 10:
The number 81 fits into 580 7 times, leaving a remainder of 13.
The number 7 becomes the next digit in our result. 
Result so far: 6459.3827
Deduct 567 from 580 and we're left with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Moving on to step 11:
130 divided by 81 is 1 with a remainder of 49.
The next digit of our result is 1. 
Result so far: 6459.38271
The remainder is 49 after subtracting 81 from 130.
Since there are no more digits in the dividend, we add a zero to the remainder making it 490, and continue the process.

Let's proceed to step 12:
When dividing 490 by 81, we get 6 with a remainder of 4.
The next digit of our result is 6. 
Result so far: 6459.382716
If we subtract 486 from 490, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

On to step 13:
If we divide 40 by 81, we get 0 and a remainder of 40.
The number 0 becomes the next digit in our result. 
Result so far: 6459.382716
Subtract 0 from 40 to get 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Going ahead to step 14:
If we divide 400 by 81, we get 4 and a remainder of 76.
Write down 4 as next digit of the result. 
Result so far: 6459.38271604
The remainder is 76 after subtracting 324 from 400.
Since there are no more digits in the dividend, we add a zero to the remainder making it 760, and continue the process.

The final outcome is 6459.38271604, with a leftover of 7.6e-08.