We look at the division of 359324 by 81 
The aim is to understand the frequency of 81 in 359324.

On to step 1:
When dividing 3 by 81, we get 0 with a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 3 to get 3.
Bring next digit (5) of the dividend behind the 3 and repeat the process: 35 / 81

Step 2:
The number 81 fits into 35 0 times, leaving a remainder of 35.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 35 to get 35.
Bring next digit (9) of the dividend behind the 35 and repeat the process: 359 / 81

Going ahead to step 3:
81 can be fit into 359 4 times, resulting in a remainder of 35.
Put 4 as the next digit of the answer. 
Result so far: 4.0
If we take 324 away from 359, we end up with 35.
Take the next digit (3) from the dividend and append it to 35, then repeat: 353 / 81

Advancing to step 4:
353 divided by 81 is 4 with a remainder of 29.
The number 4 becomes the next digit in our result. 
Result so far: 44.0
If we subtract 324 from 353, we get 29.
Take the next digit (2) from the dividend and append it to 29, then repeat: 292 / 81

On to step 5:
81 can be fit into 292 3 times, resulting in a remainder of 49.
The number 3 becomes the next digit in our result. 
Result so far: 443.0
Subtracting 243 from 292 leaves us with 49.
Take the next digit (4) from the dividend and append it to 49, then repeat: 494 / 81

Moving on to step 6:
81 goes into 494 6 times with a remainder of 8.
Put 6 as the next digit of the answer. 
Result so far: 4436.0
Deduct 486 from 494 and we're left with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Going ahead to step 7:
If we divide 80 by 81, we get 0 and a remainder of 80.
Put 0 as the next digit of the answer. 
Result so far: 4436.0
Subtracting 0 from 80 leaves us with 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Step 8:
81 can be fit into 800 9 times, resulting in a remainder of 71.
Put 9 as the next digit of the answer. 
Result so far: 4436.09
The remainder is 71 after subtracting 729 from 800.
Since there are no more digits in the dividend, we add a zero to the remainder making it 710, and continue the process.

Going ahead to step 9:
If we divide 710 by 81, we get 8 and a remainder of 62.
Put 8 as the next digit of the answer. 
Result so far: 4436.098
If we take 648 away from 710, we end up with 62.
Since there are no more digits in the dividend, we add a zero to the remainder making it 620, and continue the process.

Let's proceed to step 10:
81 can be fit into 620 7 times, resulting in a remainder of 53.
Record the quotient 7 as the next digit in the result. 
Result so far: 4436.0987
If we subtract 567 from 620, we get 53.
Since there are no more digits in the dividend, we add a zero to the remainder making it 530, and continue the process.

Let's proceed to step 11:
When dividing 530 by 81, we get 6 with a remainder of 44.
Put 6 as the next digit of the answer. 
Result so far: 4436.09876
Subtract 486 from 530 to get 44.
Since there are no more digits in the dividend, we add a zero to the remainder making it 440, and continue the process.

Advancing to step 12:
81 goes into 440 5 times with a remainder of 35.
Use 5 as the next digit of our solution. 
Result so far: 4436.098765
Subtract 405 from 440 to get 35.
Since there are no more digits in the dividend, we add a zero to the remainder making it 350, and continue the process.

On to step 13:
If we divide 350 by 81, we get 4 and a remainder of 26.
Write down 4 as next digit of the result. 
Result so far: 4436.0987654
Deduct 324 from 350 and we're left with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

Let's proceed to step 14:
260 divided by 81 is 3 with a remainder of 17.
Write down 3 as next digit of the result. 
Result so far: 4436.09876543
Subtract 243 from 260 to get 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

The final result is 4436.09876543 with a remainder of 1.7e-08.