We're dividing 665199 by 90 
The aim is to understand the frequency of 90 in 665199.

On to step 1:
When dividing 6 by 90, we get 0 with a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Append the next digit (6) from the dividend to 6 and continue with: 66 / 90

Advancing to step 2:
90 can be fit into 66 0 times, resulting in a remainder of 66.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 66 to get 66.
Include the next digit (5) from the dividend after 66, then repeat: 665 / 90

Going ahead to step 3:
The number 90 fits into 665 7 times, leaving a remainder of 35.
Write down 7 as next digit of the result. 
Result so far: 7.0
Subtract 630 from 665 to get 35.
Append the next digit (1) from the dividend to 35 and continue with: 351 / 90

On to step 4:
When dividing 351 by 90, we get 3 with a remainder of 81.
The next digit of our result is 3. 
Result so far: 73.0
Subtract 270 from 351 to get 81.
Take the next digit (9) from the dividend and append it to 81, then repeat: 819 / 90

On to step 5:
If we divide 819 by 90, we get 9 and a remainder of 9.
Record the quotient 9 as the next digit in the result. 
Result so far: 739.0
Deduct 810 from 819 and we're left with 9.
Grab the next digit (9) from the dividend, add it to 9, then carry on: 99 / 90

Moving on to step 6:
90 can be fit into 99 1 times, resulting in a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 7391.0
If we subtract 90 from 99, we get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Advancing to step 7:
90 divided by 90 is 1 with a remainder of 0.
Record the quotient 1 as the next digit in the result. 
Result so far: 7391.1
Deduct 90 from 90 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 8:
90 goes into 0 0 times with a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 7391.1
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Let's proceed to step 9:
When dividing 0 by 90, we get 0 with a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 7391.1
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final result is 7391.1 with a remainder of 0.0.