644688 ÷ 28 
The aim is to understand the frequency of 28 in 644688.

Let's proceed to step 1:
28 goes into 6 0 times with a remainder of 6.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Include the next digit (4) from the dividend after 6, then repeat: 64 / 28

Moving on to step 2:
28 goes into 64 2 times with a remainder of 8.
Use 2 as the next digit of our solution. 
Result so far: 2.0
The remainder is 8 after subtracting 56 from 64.
Fetch the next digit (4) from the dividend, attach it to 8 and continue: 84 / 28

Let's proceed to step 3:
When dividing 84 by 28, we get 3 with a remainder of 0.
The number 3 becomes the next digit in our result. 
Result so far: 23.0
The remainder is 0 after subtracting 84 from 84.
Include the next digit (6) from the dividend after 0, then repeat: 6 / 28

Going ahead to step 4:
When dividing 6 by 28, we get 0 with a remainder of 6.
The next digit of our result is 0. 
Result so far: 230.0
If we take 0 away from 6, we end up with 6.
Bring next digit (8) of the dividend behind the 6 and repeat the process: 68 / 28

Advancing to step 5:
The number 28 fits into 68 2 times, leaving a remainder of 12.
The next digit of our result is 2. 
Result so far: 2302.0
Subtract 56 from 68 to get 12.
Include the next digit (8) from the dividend after 12, then repeat: 128 / 28

Step 6:
If we divide 128 by 28, we get 4 and a remainder of 16.
The number 4 becomes the next digit in our result. 
Result so far: 23024.0
If we take 112 away from 128, we end up 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.

Going ahead to step 7:
160 divided by 28 is 5 with a remainder of 20.
The number 5 becomes the next digit in our result. 
Result so far: 23024.5
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.

Step 8:
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: 23024.57
If we take 196 away from 200, we end up 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.

Moving on to step 9:
When dividing 40 by 28, we get 1 with a remainder of 12.
Use 1 as the next digit of our solution. 
Result so far: 23024.571
The remainder is 12 after subtracting 28 from 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Let's proceed to step 10:
If we divide 120 by 28, we get 4 and a remainder of 8.
The next digit of our result is 4. 
Result so far: 23024.5714
If we subtract 112 from 120, we 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 11:
When dividing 80 by 28, we get 2 with a remainder of 24.
The next digit of our result is 2. 
Result so far: 23024.57142
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.

Let's proceed to step 12:
When dividing 240 by 28, we get 8 with a remainder of 16.
Use 8 as the next digit of our solution. 
Result so far: 23024.571428
If we take 224 away from 240, we end up 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.
Use 5 as the next digit of our solution. 
Result so far: 23024.5714285
The remainder is 20 after subtracting 140 from 160.
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 14:
200 divided by 28 is 7 with a remainder of 4.
Record the quotient 7 as the next digit in the result. 
Result so far: 23024.57142857
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.

The final result is 23024.57142857 with a remainder of 4e-09.