We look at the division of 501668 by 28 
The aim is to understand the frequency of 28 in 501668.

On to step 1:
When dividing 5 by 28, we get 0 with a remainder of 5.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 5 to get 5.
Fetch the next digit (0) from the dividend, attach it to 5 and continue: 50 / 28

Moving on to step 2:
The number 28 fits into 50 1 times, leaving a remainder of 22.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Subtract 28 from 50 to get 22.
Take the next digit (1) from the dividend and append it to 22, then repeat: 221 / 28

Moving on to step 3:
28 can be fit into 221 7 times, resulting in a remainder of 25.
Record the quotient 7 as the next digit in the result. 
Result so far: 17.0
If we subtract 196 from 221, we get 25.
Bring next digit (6) of the dividend behind the 25 and repeat the process: 256 / 28

Advancing to step 4:
256 divided by 28 is 9 with a remainder of 4.
The next digit of our result is 9. 
Result so far: 179.0
Deduct 252 from 256 and we're left with 4.
Grab the next digit (6) from the dividend, add it to 4, then carry on: 46 / 28

Advancing to step 5:
46 divided by 28 is 1 with a remainder of 18.
The number 1 becomes the next digit in our result. 
Result so far: 1791.0
The remainder is 18 after subtracting 28 from 46.
Bring next digit (8) of the dividend behind the 18 and repeat the process: 188 / 28

Step 6:
188 divided by 28 is 6 with a remainder of 20.
Record the quotient 6 as the next digit in the result. 
Result so far: 17916.0
Subtracting 168 from 188 leaves us with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Moving on to step 7:
The number 28 fits into 200 7 times, leaving a remainder of 4.
Put 7 as the next digit of the answer. 
Result so far: 17916.7
Deduct 196 from 200 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.

Advancing to step 8:
When dividing 40 by 28, we get 1 with a remainder of 12.
The number 1 becomes the next digit in our result. 
Result so far: 17916.71
If we take 28 away from 40, we end up with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

On to step 9:
The number 28 fits into 120 4 times, leaving a remainder of 8.
Put 4 as the next digit of the answer. 
Result so far: 17916.714
Subtract 112 from 120 to get 8.
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 10:
If we divide 80 by 28, we get 2 and a remainder of 24.
Write down 2 as next digit of the result. 
Result so far: 17916.7142
The remainder is 24 after subtracting 56 from 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

Going ahead to step 11:
The number 28 fits into 240 8 times, leaving a remainder of 16.
The next digit of our result is 8. 
Result so far: 17916.71428
Subtract 224 from 240 to get 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Going ahead to step 12:
When dividing 160 by 28, we get 5 with a remainder of 20.
Record the quotient 5 as the next digit in the result. 
Result so far: 17916.714285
Deduct 140 from 160 and we're left with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

On to step 13:
200 divided by 28 is 7 with a remainder of 4.
The number 7 becomes the next digit in our result. 
Result so far: 17916.7142857
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.

Moving on to step 14:
If we divide 40 by 28, we get 1 and a remainder of 12.
Use 1 as the next digit of our solution. 
Result so far: 17916.71428571
Subtract 28 from 40 to 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.

The quotient of the division is 17916.71428571, and the remainder is 1.2e-08.