637420 ÷ 90 
The aim is to understand the frequency of 90 in 637420.

Step 1:
When dividing 6 by 90, we get 0 with a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Bring next digit (3) of the dividend behind the 6 and repeat the process: 63 / 90

Moving on to step 2:
90 can be fit into 63 0 times, resulting in a remainder of 63.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 63, we get 63.
Grab the next digit (7) from the dividend, add it to 63, then carry on: 637 / 90

Step 3:
637 divided by 90 is 7 with a remainder of 7.
The number 7 becomes the next digit in our result. 
Result so far: 7.0
The remainder is 7 after subtracting 630 from 637.
Append the next digit (4) from the dividend to 7 and continue with: 74 / 90

Step 4:
The number 90 fits into 74 0 times, leaving a remainder of 74.
Write down 0 as next digit of the result. 
Result so far: 70.0
Subtracting 0 from 74 leaves us with 74.
Take the next digit (2) from the dividend and append it to 74, then repeat: 742 / 90

Step 5:
When dividing 742 by 90, we get 8 with a remainder of 22.
Put 8 as the next digit of the answer. 
Result so far: 708.0
If we take 720 away from 742, we end up with 22.
Append the next digit (0) from the dividend to 22 and continue with: 220 / 90

Going ahead to step 6:
220 divided by 90 is 2 with a remainder of 40.
The next digit of our result is 2. 
Result so far: 7082.0
Subtracting 180 from 220 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.

Moving on to step 7:
90 can be fit into 400 4 times, resulting in a remainder of 40.
Record the quotient 4 as the next digit in the result. 
Result so far: 7082.4
If we take 360 away from 400, 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:
90 can be fit into 400 4 times, resulting in a remainder of 40.
The number 4 becomes the next digit in our result. 
Result so far: 7082.44
The remainder is 40 after subtracting 360 from 400.
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 result is 7082.44 with a remainder of 0.04.