820815 divided by 90 
The aim is to understand the frequency of 90 in 820815.

Step 1:
When dividing 8 by 90, we get 0 with a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 8 leaves us with 8.
Include the next digit (2) from the dividend after 8, then repeat: 82 / 90

Advancing to step 2:
When dividing 82 by 90, we get 0 with a remainder of 82.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 82 and we're left with 82.
Append the next digit (0) from the dividend to 82 and continue with: 820 / 90

Step 3:
90 can be fit into 820 9 times, resulting in a remainder of 10.
Record the quotient 9 as the next digit in the result. 
Result so far: 9.0
Deduct 810 from 820 and we're left with 10.
Bring next digit (8) of the dividend behind the 10 and repeat the process: 108 / 90

On to step 4:
The number 90 fits into 108 1 times, leaving a remainder of 18.
Put 1 as the next digit of the answer. 
Result so far: 91.0
The remainder is 18 after subtracting 90 from 108.
Grab the next digit (1) from the dividend, add it to 18, then carry on: 181 / 90

Advancing to step 5:
90 can be fit into 181 2 times, resulting in a remainder of 1.
The number 2 becomes the next digit in our result. 
Result so far: 912.0
Deduct 180 from 181 and we're left with 1.
Take the next digit (5) from the dividend and append it to 1, then repeat: 15 / 90

Going ahead to step 6:
The number 90 fits into 15 0 times, leaving a remainder of 15.
The next digit of our result is 0. 
Result so far: 9120.0
Subtracting 0 from 15 leaves us with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Let's proceed to step 7:
If we divide 150 by 90, we get 1 and a remainder of 60.
Record the quotient 1 as the next digit in the result. 
Result so far: 9120.1
Subtract 90 from 150 to get 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

Going ahead to step 8:
When dividing 600 by 90, we get 6 with a remainder of 60.
Record the quotient 6 as the next digit in the result. 
Result so far: 9120.16
Subtracting 540 from 600 leaves us with 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

Advancing to step 9:
600 divided by 90 is 6 with a remainder of 60.
Put 6 as the next digit of the answer. 
Result so far: 9120.166
Subtract 540 from 600 to get 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

Our division results in 9120.166 with a remaining 0.006.