Let's divide 668353 by 90
The aim is to understand the frequency of 90 in 668353.

Step 1:
The number 90 fits into 6 0 times, leaving a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Include the next digit (6) from the dividend after 6, then repeat: 66 / 90

Moving on to step 2:
If we divide 66 by 90, we get 0 and a remainder of 66.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 66, we end up with 66.
Append the next digit (8) from the dividend to 66 and continue with: 668 / 90

Step 3:
The number 90 fits into 668 7 times, leaving a remainder of 38.
Write down 7 as next digit of the result. 
Result so far: 7.0
Subtracting 630 from 668 leaves us with 38.
Take the next digit (3) from the dividend and append it to 38, then repeat: 383 / 90

On to step 4:
The number 90 fits into 383 4 times, leaving a remainder of 23.
The next digit of our result is 4. 
Result so far: 74.0
Subtract 360 from 383 to get 23.
Append the next digit (5) from the dividend to 23 and continue with: 235 / 90

Step 5:
If we divide 235 by 90, we get 2 and a remainder of 55.
Use 2 as the next digit of our solution. 
Result so far: 742.0
If we take 180 away from 235, we end up with 55.
Include the next digit (3) from the dividend after 55, then repeat: 553 / 90

On to step 6:
90 goes into 553 6 times with a remainder of 13.
Record the quotient 6 as the next digit in the result. 
Result so far: 7426.0
If we subtract 540 from 553, we get 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

On to step 7:
The number 90 fits into 130 1 times, leaving a remainder of 40.
The number 1 becomes the next digit in our result. 
Result so far: 7426.1
If we take 90 away from 130, 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.

Step 8:
If we divide 400 by 90, we get 4 and a remainder of 40.
Write down 4 as next digit of the result. 
Result so far: 7426.14
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:
If we divide 400 by 90, we get 4 and a remainder of 40.
Put 4 as the next digit of the answer. 
Result so far: 7426.144
Subtracting 360 from 400 leaves us 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.

After the division, we end up with 7426.144 and a remainder of 0.004.