We look at the division of 398666 by 72 
The aim is to understand the frequency of 72 in 398666.

Moving on to step 1:
The number 72 fits into 3 0 times, leaving a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 3 after subtracting 0 from 3.
Append the next digit (9) from the dividend to 3 and continue with: 39 / 72

On to step 2:
When dividing 39 by 72, we get 0 with a remainder of 39.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 39 to get 39.
Include the next digit (8) from the dividend after 39, then repeat: 398 / 72

Going ahead to step 3:
The number 72 fits into 398 5 times, leaving a remainder of 38.
Put 5 as the next digit of the answer. 
Result so far: 5.0
The remainder is 38 after subtracting 360 from 398.
Bring next digit (6) of the dividend behind the 38 and repeat the process: 386 / 72

Going ahead to step 4:
386 divided by 72 is 5 with a remainder of 26.
Write down 5 as next digit of the result. 
Result so far: 55.0
If we subtract 360 from 386, we get 26.
Include the next digit (6) from the dividend after 26, then repeat: 266 / 72

Let's proceed to step 5:
When dividing 266 by 72, we get 3 with a remainder of 50.
The number 3 becomes the next digit in our result. 
Result so far: 553.0
Subtract 216 from 266 to get 50.
Bring next digit (6) of the dividend behind the 50 and repeat the process: 506 / 72

Moving on to step 6:
When dividing 506 by 72, we get 7 with a remainder of 2.
The next digit of our result is 7. 
Result so far: 5537.0
Subtract 504 from 506 to get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Step 7:
If we divide 20 by 72, we get 0 and a remainder of 20.
The number 0 becomes the next digit in our result. 
Result so far: 5537.0
If we subtract 0 from 20, 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.

Moving on to step 8:
When dividing 200 by 72, we get 2 with a remainder of 56.
The next digit of our result is 2. 
Result so far: 5537.02
The remainder is 56 after subtracting 144 from 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 560, and continue the process.

Moving on to step 9:
When dividing 560 by 72, we get 7 with a remainder of 56.
Use 7 as the next digit of our solution. 
Result so far: 5537.027
The remainder is 56 after subtracting 504 from 560.
Since there are no more digits in the dividend, we add a zero to the remainder making it 560, and continue the process.

On to step 10:
The number 72 fits into 560 7 times, leaving a remainder of 56.
Write down 7 as next digit of the result. 
Result so far: 5537.0277
Subtracting 504 from 560 leaves us with 56.
Since there are no more digits in the dividend, we add a zero to the remainder making it 560, and continue the process.

The final outcome is 5537.0277, with a leftover of 0.00056.