We look at the division of 75648 by 90 
The aim is to understand the frequency of 90 in 75648.

On to step 1:
When dividing 7 by 90, we get 0 with a remainder of 7.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 7, we get 7.
Take the next digit (5) from the dividend and append it to 7, then repeat: 75 / 90

Moving on to step 2:
The number 90 fits into 75 0 times, leaving a remainder of 75.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 75 after subtracting 0 from 75.
Take the next digit (6) from the dividend and append it to 75, then repeat: 756 / 90

Going ahead to step 3:
90 can be fit into 756 8 times, resulting in a remainder of 36.
The next digit of our result is 8. 
Result so far: 8.0
Deduct 720 from 756 and we're left with 36.
Grab the next digit (4) from the dividend, add it to 36, then carry on: 364 / 90

Let's proceed to step 4:
The number 90 fits into 364 4 times, leaving a remainder of 4.
Write down 4 as next digit of the result. 
Result so far: 84.0
The remainder is 4 after subtracting 360 from 364.
Append the next digit (8) from the dividend to 4 and continue with: 48 / 90

Going ahead to step 5:
If we divide 48 by 90, we get 0 and a remainder of 48.
Put 0 as the next digit of the answer. 
Result so far: 840.0
Subtracting 0 from 48 leaves us with 48.
Since there are no more digits in the dividend, we add a zero to the remainder making it 480, and continue the process.

Advancing to step 6:
If we divide 480 by 90, we get 5 and a remainder of 30.
The number 5 becomes the next digit in our result. 
Result so far: 840.5
If we subtract 450 from 480, we get 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Let's proceed to step 7:
300 divided by 90 is 3 with a remainder of 30.
Write down 3 as next digit of the result. 
Result so far: 840.53
If we subtract 270 from 300, we get 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Moving on to step 8:
90 goes into 300 3 times with a remainder of 30.
Use 3 as the next digit of our solution. 
Result so far: 840.533
If we subtract 270 from 300, we get 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

The final result is 840.533 with a remainder of 0.003.