We look at the division of 831399 by 28 
The aim is to understand the frequency of 28 in 831399.

On to step 1:
When dividing 8 by 28, we get 0 with a remainder of 8.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 8, we get 8.
Fetch the next digit (3) from the dividend, attach it to 8 and continue: 83 / 28

Step 2:
The number 28 fits into 83 2 times, leaving a remainder of 27.
Use 2 as the next digit of our solution. 
Result so far: 2.0
If we subtract 56 from 83, we get 27.
Include the next digit (1) from the dividend after 27, then repeat: 271 / 28

Step 3:
271 divided by 28 is 9 with a remainder of 19.
The number 9 becomes the next digit in our result. 
Result so far: 29.0
If we subtract 252 from 271, we get 19.
Fetch the next digit (3) from the dividend, attach it to 19 and continue: 193 / 28

Moving on to step 4:
28 can be fit into 193 6 times, resulting in a remainder of 25.
Put 6 as the next digit of the answer. 
Result so far: 296.0
Subtract 168 from 193 to get 25.
Grab the next digit (9) from the dividend, add it to 25, then carry on: 259 / 28

Going ahead to step 5:
When dividing 259 by 28, we get 9 with a remainder of 7.
The next digit of our result is 9. 
Result so far: 2969.0
Deduct 252 from 259 and we're left with 7.
Append the next digit (9) from the dividend to 7 and continue with: 79 / 28

Advancing to step 6:
When dividing 79 by 28, we get 2 with a remainder of 23.
Use 2 as the next digit of our solution. 
Result so far: 29692.0
Deduct 56 from 79 and we're left with 23.
Since there are no more digits in the dividend, we add a zero to the remainder making it 230, and continue the process.

Advancing to step 7:
28 goes into 230 8 times with a remainder of 6.
Use 8 as the next digit of our solution. 
Result so far: 29692.8
The remainder is 6 after subtracting 224 from 230.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Moving on to step 8:
If we divide 60 by 28, we get 2 and a remainder of 4.
Record the quotient 2 as the next digit in the result. 
Result so far: 29692.82
Deduct 56 from 60 and we're left with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Step 9:
The number 28 fits into 40 1 times, leaving a remainder of 12.
Record the quotient 1 as the next digit in the result. 
Result so far: 29692.821
If we subtract 28 from 40, we get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Step 10:
If we divide 120 by 28, we get 4 and a remainder of 8.
Put 4 as the next digit of the answer. 
Result so far: 29692.8214
The remainder is 8 after subtracting 112 from 120.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Let's proceed to step 11:
The number 28 fits into 80 2 times, leaving a remainder of 24.
Record the quotient 2 as the next digit in the result. 
Result so far: 29692.82142
Subtract 56 from 80 to get 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

Step 12:
240 divided by 28 is 8 with a remainder of 16.
Put 8 as the next digit of the answer. 
Result so far: 29692.821428
Deduct 224 from 240 and we're left with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Step 13:
28 goes into 160 5 times with a remainder of 20.
Write down 5 as next digit of the result. 
Result so far: 29692.8214285
If we subtract 140 from 160, we get 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Going ahead to step 14:
If we divide 200 by 28, we get 7 and a remainder of 4.
Record the quotient 7 as the next digit in the result. 
Result so far: 29692.82142857
If we subtract 196 from 200, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

The final outcome is 29692.82142857, with a leftover of 4e-09.