424625 divided by 90 
The aim is to understand the frequency of 90 in 424625.

Step 1:
When dividing 4 by 90, we get 0 with a remainder of 4.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 4 after subtracting 0 from 4.
Include the next digit (2) from the dividend after 4, then repeat: 42 / 90

On to step 2:
90 goes into 42 0 times with a remainder of 42.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 42 and we're left with 42.
Append the next digit (4) from the dividend to 42 and continue with: 424 / 90

Step 3:
The number 90 fits into 424 4 times, leaving a remainder of 64.
The number 4 becomes the next digit in our result. 
Result so far: 4.0
If we take 360 away from 424, we end up with 64.
Grab the next digit (6) from the dividend, add it to 64, then carry on: 646 / 90

Moving on to step 4:
646 divided by 90 is 7 with a remainder of 16.
Use 7 as the next digit of our solution. 
Result so far: 47.0
If we take 630 away from 646, we end up with 16.
Append the next digit (2) from the dividend to 16 and continue with: 162 / 90

Moving on to step 5:
When dividing 162 by 90, we get 1 with a remainder of 72.
Put 1 as the next digit of the answer. 
Result so far: 471.0
If we subtract 90 from 162, we get 72.
Take the next digit (5) from the dividend and append it to 72, then repeat: 725 / 90

Moving on to step 6:
90 goes into 725 8 times with a remainder of 5.
Write down 8 as next digit of the result. 
Result so far: 4718.0
Subtracting 720 from 725 leaves us with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Step 7:
90 can be fit into 50 0 times, resulting in a remainder of 50.
The next digit of our result is 0. 
Result so far: 4718.0
If we take 0 away from 50, we end up with 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

Let's proceed to step 8:
The number 90 fits into 500 5 times, leaving a remainder of 50.
Record the quotient 5 as the next digit in the result. 
Result so far: 4718.05
Deduct 450 from 500 and we're left with 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

Advancing to step 9:
When dividing 500 by 90, we get 5 with a remainder of 50.
Use 5 as the next digit of our solution. 
Result so far: 4718.055
If we subtract 450 from 500, we get 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

The final result is 4718.055 with a remainder of 0.005.