100989 divided by 90 
The aim is to understand the frequency of 90 in 100989.

Advancing to step 1:
The number 90 fits into 1 0 times, leaving a remainder of 1.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 1 after subtracting 0 from 1.
Grab the next digit (0) from the dividend, add it to 1, then carry on: 10 / 90

On to step 2:
10 divided by 90 is 0 with a remainder of 10.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 10 to get 10.
Bring next digit (0) of the dividend behind the 10 and repeat the process: 100 / 90

Moving on to step 3:
90 can be fit into 100 1 times, resulting in a remainder of 10.
Put 1 as the next digit of the answer. 
Result so far: 1.0
Subtracting 90 from 100 leaves us with 10.
Append the next digit (9) from the dividend to 10 and continue with: 109 / 90

Moving on to step 4:
90 goes into 109 1 times with a remainder of 19.
Record the quotient 1 as the next digit in the result. 
Result so far: 11.0
If we subtract 90 from 109, we get 19.
Fetch the next digit (8) from the dividend, attach it to 19 and continue: 198 / 90

Moving on to step 5:
The number 90 fits into 198 2 times, leaving a remainder of 18.
Put 2 as the next digit of the answer. 
Result so far: 112.0
Subtract 180 from 198 to get 18.
Fetch the next digit (9) from the dividend, attach it to 18 and continue: 189 / 90

Advancing to step 6:
90 can be fit into 189 2 times, resulting in a remainder of 9.
Write down 2 as next digit of the result. 
Result so far: 1122.0
If we take 180 away from 189, we end up with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Let's proceed to step 7:
If we divide 90 by 90, we get 1 and a remainder of 0.
Write down 1 as next digit of the result. 
Result so far: 1122.1
Subtract 90 from 90 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 8:
90 goes into 0 0 times with a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 1122.1
If we take 0 away from 0, we end up with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Step 9:
The number 90 fits into 0 0 times, leaving a remainder of 0.
The next digit of our result is 0. 
Result so far: 1122.1
If we subtract 0 from 0, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final result is 1122.1 with a remainder of 0.0.