Let's divide 664921 by 80
The aim is to understand the frequency of 80 in 664921.

Step 1:
When dividing 6 by 80, we get 0 with a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Include the next digit (6) from the dividend after 6, then repeat: 66 / 80

Let's proceed to step 2:
80 can be fit into 66 0 times, resulting in a remainder of 66.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 66 leaves us with 66.
Take the next digit (4) from the dividend and append it to 66, then repeat: 664 / 80

Step 3:
664 divided by 80 is 8 with a remainder of 24.
Use 8 as the next digit of our solution. 
Result so far: 8.0
The remainder is 24 after subtracting 640 from 664.
Bring next digit (9) of the dividend behind the 24 and repeat the process: 249 / 80

Moving on to step 4:
The number 80 fits into 249 3 times, leaving a remainder of 9.
The next digit of our result is 3. 
Result so far: 83.0
The remainder is 9 after subtracting 240 from 249.
Append the next digit (2) from the dividend to 9 and continue with: 92 / 80

On to step 5:
80 goes into 92 1 times with a remainder of 12.
Write down 1 as next digit of the result. 
Result so far: 831.0
Subtracting 80 from 92 leaves us with 12.
Append the next digit (1) from the dividend to 12 and continue with: 121 / 80

Let's proceed to step 6:
80 can be fit into 121 1 times, resulting in a remainder of 41.
Use 1 as the next digit of our solution. 
Result so far: 8311.0
If we subtract 80 from 121, we get 41.
Since there are no more digits in the dividend, we add a zero to the remainder making it 410, and continue the process.

Let's proceed to step 7:
80 goes into 410 5 times with a remainder of 10.
Put 5 as the next digit of the answer. 
Result so far: 8311.5
Subtract 400 from 410 to get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 8:
The number 80 fits into 100 1 times, leaving a remainder of 20.
Put 1 as the next digit of the answer. 
Result so far: 8311.51
If we take 80 away from 100, we end up 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 9:
80 can be fit into 200 2 times, resulting in a remainder of 40.
Write down 2 as next digit of the result. 
Result so far: 8311.512
If we subtract 160 from 200, we get 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Let's proceed to step 10:
80 goes into 400 5 times with a remainder of 0.
Put 5 as the next digit of the answer. 
Result so far: 8311.5125
If we subtract 400 from 400, 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.

Moving on to step 11:
The number 80 fits into 0 0 times, leaving a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 8311.5125
The remainder is 0 after subtracting 0 from 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 12:
0 divided by 80 is 0 with a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 8311.5125
Deduct 0 from 0 and we're left 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.

The final result is 8311.5125 with a remainder of 0.0.