We look at the division of 290671 by 90 
The aim is to understand the frequency of 90 in 290671.

Advancing to step 1:
The number 90 fits into 2 0 times, leaving a remainder of 2.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 2 leaves us with 2.
Append the next digit (9) from the dividend to 2 and continue with: 29 / 90

Let's proceed to step 2:
90 can be fit into 29 0 times, resulting in a remainder of 29.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 29, we end up with 29.
Take the next digit (0) from the dividend and append it to 29, then repeat: 290 / 90

On to step 3:
90 can be fit into 290 3 times, resulting in a remainder of 20.
Use 3 as the next digit of our solution. 
Result so far: 3.0
If we take 270 away from 290, we end up with 20.
Take the next digit (6) from the dividend and append it to 20, then repeat: 206 / 90

On to step 4:
90 goes into 206 2 times with a remainder of 26.
The next digit of our result is 2. 
Result so far: 32.0
If we subtract 180 from 206, we get 26.
Fetch the next digit (7) from the dividend, attach it to 26 and continue: 267 / 90

Step 5:
If we divide 267 by 90, we get 2 and a remainder of 87.
Write down 2 as next digit of the result. 
Result so far: 322.0
Deduct 180 from 267 and we're left with 87.
Include the next digit (1) from the dividend after 87, then repeat: 871 / 90

Step 6:
871 divided by 90 is 9 with a remainder of 61.
Put 9 as the next digit of the answer. 
Result so far: 3229.0
Subtract 810 from 871 to get 61.
Since there are no more digits in the dividend, we add a zero to the remainder making it 610, and continue the process.

Step 7:
610 divided by 90 is 6 with a remainder of 70.
The number 6 becomes the next digit in our result. 
Result so far: 3229.6
If we take 540 away from 610, we end up with 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

Moving on to step 8:
700 divided by 90 is 7 with a remainder of 70.
The number 7 becomes the next digit in our result. 
Result so far: 3229.67
If we subtract 630 from 700, we get 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

Let's proceed to step 9:
The number 90 fits into 700 7 times, leaving a remainder of 70.
Write down 7 as next digit of the result. 
Result so far: 3229.677
Subtract 630 from 700 to get 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

After the division, we end up with 3229.677 and a remainder of 0.007.