We look at the division of 904410 by 81 
The aim is to understand the frequency of 81 in 904410.

On to step 1:
9 divided by 81 is 0 with a remainder of 9.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 9, we get 9.
Grab the next digit (0) from the dividend, add it to 9, then carry on: 90 / 81

Advancing to step 2:
The number 81 fits into 90 1 times, leaving a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 1.0
Subtracting 81 from 90 leaves us with 9.
Include the next digit (4) from the dividend after 9, then repeat: 94 / 81

On to step 3:
When dividing 94 by 81, we get 1 with a remainder of 13.
Record the quotient 1 as the next digit in the result. 
Result so far: 11.0
If we take 81 away from 94, we end up with 13.
Append the next digit (4) from the dividend to 13 and continue with: 134 / 81

Let's proceed to step 4:
When dividing 134 by 81, we get 1 with a remainder of 53.
Record the quotient 1 as the next digit in the result. 
Result so far: 111.0
Subtract 81 from 134 to get 53.
Bring next digit (1) of the dividend behind the 53 and repeat the process: 531 / 81

Step 5:
When dividing 531 by 81, we get 6 with a remainder of 45.
The number 6 becomes the next digit in our result. 
Result so far: 1116.0
Deduct 486 from 531 and we're left with 45.
Grab the next digit (0) from the dividend, add it to 45, then carry on: 450 / 81

Moving on to step 6:
When dividing 450 by 81, we get 5 with a remainder of 45.
Use 5 as the next digit of our solution. 
Result so far: 11165.0
Subtract 405 from 450 to get 45.
Since there are no more digits in the dividend, we add a zero to the remainder making it 450, and continue the process.

Step 7:
When dividing 450 by 81, we get 5 with a remainder of 45.
Record the quotient 5 as the next digit in the result. 
Result so far: 11165.5
Deduct 405 from 450 and we're left with 45.
Since there are no more digits in the dividend, we add a zero to the remainder making it 450, and continue the process.

On to step 8:
If we divide 450 by 81, we get 5 and a remainder of 45.
The number 5 becomes the next digit in our result. 
Result so far: 11165.55
Subtracting 405 from 450 leaves us with 45.
Since there are no more digits in the dividend, we add a zero to the remainder making it 450, and continue the process.

Our division results in 11165.55 with a remaining 0.045.