We're dividing 666357 by 90 
The aim is to understand the frequency of 90 in 666357.

Moving on to step 1:
6 divided by 90 is 0 with a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 6 to get 6.
Include the next digit (6) from the dividend after 6, then repeat: 66 / 90

Advancing to step 2:
66 divided by 90 is 0 with a remainder of 66.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 66 and we're left with 66.
Grab the next digit (6) from the dividend, add it to 66, then carry on: 666 / 90

Moving on to step 3:
90 can be fit into 666 7 times, resulting in a remainder of 36.
Use 7 as the next digit of our solution. 
Result so far: 7.0
Subtracting 630 from 666 leaves us with 36.
Grab the next digit (3) from the dividend, add it to 36, then carry on: 363 / 90

Moving on to step 4:
If we divide 363 by 90, we get 4 and a remainder of 3.
The next digit of our result is 4. 
Result so far: 74.0
Deduct 360 from 363 and we're left with 3.
Bring next digit (5) of the dividend behind the 3 and repeat the process: 35 / 90

Going ahead to step 5:
90 goes into 35 0 times with a remainder of 35.
Use 0 as the next digit of our solution. 
Result so far: 740.0
Deduct 0 from 35 and we're left with 35.
Append the next digit (7) from the dividend to 35 and continue with: 357 / 90

Moving on to step 6:
357 divided by 90 is 3 with a remainder of 87.
Put 3 as the next digit of the answer. 
Result so far: 7403.0
If we subtract 270 from 357, we get 87.
Since there are no more digits in the dividend, we add a zero to the remainder making it 870, and continue the process.

Step 7:
90 goes into 870 9 times with a remainder of 60.
The next digit of our result is 9. 
Result so far: 7403.9
The remainder is 60 after subtracting 810 from 870.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

Step 8:
If we divide 600 by 90, we get 6 and a remainder of 60.
Use 6 as the next digit of our solution. 
Result so far: 7403.96
Subtracting 540 from 600 leaves us 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.

Advancing to step 9:
If we divide 600 by 90, we get 6 and a remainder of 60.
Record the quotient 6 as the next digit in the result. 
Result so far: 7403.966
Subtracting 540 from 600 leaves us 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 7403.966 with a remainder of 0.006.