We look at the division of 187873 by 90 
The aim is to understand the frequency of 90 in 187873.

Advancing to step 1:
90 can be fit into 1 0 times, resulting in a remainder of 1.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 1, we end up with 1.
Bring next digit (8) of the dividend behind the 1 and repeat the process: 18 / 90

On to step 2:
When dividing 18 by 90, we get 0 with a remainder of 18.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 18, we get 18.
Append the next digit (7) from the dividend to 18 and continue with: 187 / 90

Let's proceed to step 3:
90 goes into 187 2 times with a remainder of 7.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
If we take 180 away from 187, we end up with 7.
Append the next digit (8) from the dividend to 7 and continue with: 78 / 90

Moving on to step 4:
The number 90 fits into 78 0 times, leaving a remainder of 78.
The next digit of our result is 0. 
Result so far: 20.0
Deduct 0 from 78 and we're left with 78.
Take the next digit (7) from the dividend and append it to 78, then repeat: 787 / 90

Going ahead to step 5:
787 divided by 90 is 8 with a remainder of 67.
Use 8 as the next digit of our solution. 
Result so far: 208.0
If we take 720 away from 787, we end up with 67.
Take the next digit (3) from the dividend and append it to 67, then repeat: 673 / 90

Step 6:
The number 90 fits into 673 7 times, leaving a remainder of 43.
Record the quotient 7 as the next digit in the result. 
Result so far: 2087.0
Subtracting 630 from 673 leaves us with 43.
Since there are no more digits in the dividend, we add a zero to the remainder making it 430, and continue the process.

Moving on to step 7:
430 divided by 90 is 4 with a remainder of 70.
Put 4 as the next digit of the answer. 
Result so far: 2087.4
The remainder is 70 after subtracting 360 from 430.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

On to step 8:
When dividing 700 by 90, we get 7 with a remainder of 70.
The number 7 becomes the next digit in our result. 
Result so far: 2087.47
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.

Step 9:
90 can be fit into 700 7 times, resulting in a remainder of 70.
Record the quotient 7 as the next digit in the result. 
Result so far: 2087.477
Subtracting 630 from 700 leaves us 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.

The final result is 2087.477 with a remainder of 0.007.