We look at the division of 659776 by 90 
The aim is to understand the frequency of 90 in 659776.

Moving on to step 1:
If we divide 6 by 90, we get 0 and a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Include the next digit (5) from the dividend after 6, then repeat: 65 / 90

Let's proceed to step 2:
If we divide 65 by 90, we get 0 and a remainder of 65.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 65, we end up with 65.
Grab the next digit (9) from the dividend, add it to 65, then carry on: 659 / 90

Step 3:
659 divided by 90 is 7 with a remainder of 29.
Write down 7 as next digit of the result. 
Result so far: 7.0
The remainder is 29 after subtracting 630 from 659.
Take the next digit (7) from the dividend and append it to 29, then repeat: 297 / 90

Moving on to step 4:
297 divided by 90 is 3 with a remainder of 27.
The number 3 becomes the next digit in our result. 
Result so far: 73.0
If we take 270 away from 297, we end up with 27.
Grab the next digit (7) from the dividend, add it to 27, then carry on: 277 / 90

Let's proceed to step 5:
90 can be fit into 277 3 times, resulting in a remainder of 7.
Record the quotient 3 as the next digit in the result. 
Result so far: 733.0
Subtract 270 from 277 to get 7.
Take the next digit (6) from the dividend and append it to 7, then repeat: 76 / 90

On to step 6:
When dividing 76 by 90, we get 0 with a remainder of 76.
Use 0 as the next digit of our solution. 
Result so far: 7330.0
If we subtract 0 from 76, we get 76.
Since there are no more digits in the dividend, we add a zero to the remainder making it 760, and continue the process.

Let's proceed to step 7:
If we divide 760 by 90, we get 8 and a remainder of 40.
Record the quotient 8 as the next digit in the result. 
Result so far: 7330.8
If we take 720 away from 760, we end up with 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Advancing to step 8:
When dividing 400 by 90, we get 4 with a remainder of 40.
Use 4 as the next digit of our solution. 
Result so far: 7330.84
Subtract 360 from 400 to get 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Advancing to step 9:
400 divided by 90 is 4 with a remainder of 40.
The next digit of our result is 4. 
Result so far: 7330.844
Subtract 360 from 400 to get 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

The final outcome is 7330.844, with a leftover of 0.004.