We look at the division of 878880 by 90 
The aim is to understand the frequency of 90 in 878880.

Moving on to step 1:
When dividing 8 by 90, we get 0 with a remainder of 8.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 8 after subtracting 0 from 8.
Append the next digit (7) from the dividend to 8 and continue with: 87 / 90

Step 2:
The number 90 fits into 87 0 times, leaving a remainder of 87.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 87, we get 87.
Bring next digit (8) of the dividend behind the 87 and repeat the process: 878 / 90

Advancing to step 3:
90 goes into 878 9 times with a remainder of 68.
Record the quotient 9 as the next digit in the result. 
Result so far: 9.0
Deduct 810 from 878 and we're left with 68.
Grab the next digit (8) from the dividend, add it to 68, then carry on: 688 / 90

Moving on to step 4:
The number 90 fits into 688 7 times, leaving a remainder of 58.
The number 7 becomes the next digit in our result. 
Result so far: 97.0
The remainder is 58 after subtracting 630 from 688.
Append the next digit (8) from the dividend to 58 and continue with: 588 / 90

Step 5:
The number 90 fits into 588 6 times, leaving a remainder of 48.
Put 6 as the next digit of the answer. 
Result so far: 976.0
If we subtract 540 from 588, we get 48.
Include the next digit (0) from the dividend after 48, then repeat: 480 / 90

Let's proceed to step 6:
If we divide 480 by 90, we get 5 and a remainder of 30.
Record the quotient 5 as the next digit in the result. 
Result so far: 9765.0
Subtracting 450 from 480 leaves us with 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Advancing to step 7:
90 can be fit into 300 3 times, resulting in a remainder of 30.
Put 3 as the next digit of the answer. 
Result so far: 9765.3
The remainder is 30 after subtracting 270 from 300.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Advancing to step 8:
If we divide 300 by 90, we get 3 and a remainder of 30.
Record the quotient 3 as the next digit in the result. 
Result so far: 9765.33
If we subtract 270 from 300, we get 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

After the division, we end up with 9765.33 and a remainder of 0.03.