We look at the division of 654099 by 90 
The aim is to understand the frequency of 90 in 654099.

On to step 1:
6 divided by 90 is 0 with a remainder of 6.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Take the next digit (5) from the dividend and append it to 6, then repeat: 65 / 90

Advancing to step 2:
90 goes into 65 0 times with a remainder of 65.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 65 to get 65.
Grab the next digit (4) from the dividend, add it to 65, then carry on: 654 / 90

Step 3:
90 goes into 654 7 times with a remainder of 24.
Record the quotient 7 as the next digit in the result. 
Result so far: 7.0
Deduct 630 from 654 and we're left with 24.
Include the next digit (0) from the dividend after 24, then repeat: 240 / 90

Advancing to step 4:
If we divide 240 by 90, we get 2 and a remainder of 60.
The number 2 becomes the next digit in our result. 
Result so far: 72.0
Subtracting 180 from 240 leaves us with 60.
Fetch the next digit (9) from the dividend, attach it to 60 and continue: 609 / 90

Step 5:
When dividing 609 by 90, we get 6 with a remainder of 69.
The number 6 becomes the next digit in our result. 
Result so far: 726.0
Deduct 540 from 609 and we're left with 69.
Include the next digit (9) from the dividend after 69, then repeat: 699 / 90

Advancing to step 6:
90 goes into 699 7 times with a remainder of 69.
Write down 7 as next digit of the result. 
Result so far: 7267.0
Deduct 630 from 699 and we're left with 69.
Since there are no more digits in the dividend, we add a zero to the remainder making it 690, and continue the process.

Let's proceed to step 7:
90 can be fit into 690 7 times, resulting in a remainder of 60.
Write down 7 as next digit of the result. 
Result so far: 7267.7
If we subtract 630 from 690, we 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.

On to step 8:
When dividing 600 by 90, we get 6 with a remainder of 60.
Write down 6 as next digit of the result. 
Result so far: 7267.76
If we subtract 540 from 600, we 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.

Let's proceed to step 9:
600 divided by 90 is 6 with a remainder of 60.
Write down 6 as next digit of the result. 
Result so far: 7267.766
Deduct 540 from 600 and we're left 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.

The final result is 7267.766 with a remainder of 0.006.