We look at the division of 91428961 by 123 
The aim is to understand the frequency of 123 in 91428961.

Step 1:
123 can be fit into 9 0 times, resulting in a remainder of 9.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 9, we end up with 9.
Bring next digit (1) of the dividend behind the 9 and repeat the process: 91 / 123

On to step 2:
The number 123 fits into 91 0 times, leaving a remainder of 91.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 91, we get 91.
Include the next digit (4) from the dividend after 91, then repeat: 914 / 123

Let's proceed to step 3:
If we divide 914 by 123, we get 7 and a remainder of 53.
The number 7 becomes the next digit in our result. 
Result so far: 7.0
Subtracting 861 from 914 leaves us with 53.
Fetch the next digit (2) from the dividend, attach it to 53 and continue: 532 / 123

Advancing to step 4:
The number 123 fits into 532 4 times, leaving a remainder of 40.
Record the quotient 4 as the next digit in the result. 
Result so far: 74.0
Deduct 492 from 532 and we're left with 40.
Bring next digit (8) of the dividend behind the 40 and repeat the process: 408 / 123

Going ahead to step 5:
The number 123 fits into 408 3 times, leaving a remainder of 39.
Put 3 as the next digit of the answer. 
Result so far: 743.0
If we take 369 away from 408, we end up with 39.
Grab the next digit (9) from the dividend, add it to 39, then carry on: 399 / 123

Advancing to step 6:
123 can be fit into 399 3 times, resulting in a remainder of 30.
Use 3 as the next digit of our solution. 
Result so far: 7433.0
Deduct 369 from 399 and we're left with 30.
Include the next digit (6) from the dividend after 30, then repeat: 306 / 123

Step 7:
123 can be fit into 306 2 times, resulting in a remainder of 60.
The number 2 becomes the next digit in our result. 
Result so far: 74332.0
If we subtract 246 from 306, we get 60.
Take the next digit (1) from the dividend and append it to 60, then repeat: 601 / 123

Moving on to step 8:
If we divide 601 by 123, we get 4 and a remainder of 109.
The next digit of our result is 4. 
Result so far: 743324.0
If we take 492 away from 601, we end up with 109.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1090, and continue the process.

Let's proceed to step 9:
123 can be fit into 1090 8 times, resulting in a remainder of 106.
The next digit of our result is 8. 
Result so far: 743324.8
If we take 984 away from 1090, we end up with 106.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1060, and continue the process.

Step 10:
123 can be fit into 1060 8 times, resulting in a remainder of 76.
Write down 8 as next digit of the result. 
Result so far: 743324.88
If we subtract 984 from 1060, we get 76.
Since there are no more digits in the dividend, we add a zero to the remainder making it 760, and continue the process.

After the division, we end up with 743324.88 and a remainder of 0.076.