We look at the division of 286172 by 90 
The aim is to understand the frequency of 90 in 286172.

Let's proceed to step 1:
The number 90 fits into 2 0 times, leaving a remainder of 2.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 2, we get 2.
Include the next digit (8) from the dividend after 2, then repeat: 28 / 90

Let's proceed to step 2:
28 divided by 90 is 0 with a remainder of 28.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 28, we end up with 28.
Append the next digit (6) from the dividend to 28 and continue with: 286 / 90

Advancing to step 3:
90 can be fit into 286 3 times, resulting in a remainder of 16.
The number 3 becomes the next digit in our result. 
Result so far: 3.0
If we take 270 away from 286, we end up with 16.
Include the next digit (1) from the dividend after 16, then repeat: 161 / 90

Step 4:
90 goes into 161 1 times with a remainder of 71.
Put 1 as the next digit of the answer. 
Result so far: 31.0
If we subtract 90 from 161, we get 71.
Append the next digit (7) from the dividend to 71 and continue with: 717 / 90

Step 5:
90 goes into 717 7 times with a remainder of 87.
The number 7 becomes the next digit in our result. 
Result so far: 317.0
Subtracting 630 from 717 leaves us with 87.
Grab the next digit (2) from the dividend, add it to 87, then carry on: 872 / 90

Advancing to step 6:
90 goes into 872 9 times with a remainder of 62.
Record the quotient 9 as the next digit in the result. 
Result so far: 3179.0
Deduct 810 from 872 and we're left with 62.
Since there are no more digits in the dividend, we add a zero to the remainder making it 620, and continue the process.

Going ahead to step 7:
When dividing 620 by 90, we get 6 with a remainder of 80.
The number 6 becomes the next digit in our result. 
Result so far: 3179.6
The remainder is 80 after subtracting 540 from 620.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Step 8:
When dividing 800 by 90, we get 8 with a remainder of 80.
The next digit of our result is 8. 
Result so far: 3179.68
Subtract 720 from 800 to get 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Advancing to step 9:
The number 90 fits into 800 8 times, leaving a remainder of 80.
Record the quotient 8 as the next digit in the result. 
Result so far: 3179.688
If we subtract 720 from 800, we get 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

The final outcome is 3179.688, with a leftover of 0.008.