We're dividing 399521 by 72 
The aim is to understand the frequency of 72 in 399521.

Going ahead to step 1:
72 goes into 3 0 times with a remainder of 3.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 3 after subtracting 0 from 3.
Fetch the next digit (9) from the dividend, attach it to 3 and continue: 39 / 72

Let's proceed to step 2:
When dividing 39 by 72, we get 0 with a remainder of 39.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 39 after subtracting 0 from 39.
Fetch the next digit (9) from the dividend, attach it to 39 and continue: 399 / 72

Advancing to step 3:
The number 72 fits into 399 5 times, leaving a remainder of 39.
The next digit of our result is 5. 
Result so far: 5.0
Subtract 360 from 399 to get 39.
Grab the next digit (5) from the dividend, add it to 39, then carry on: 395 / 72

Advancing to step 4:
72 can be fit into 395 5 times, resulting in a remainder of 35.
Record the quotient 5 as the next digit in the result. 
Result so far: 55.0
Subtract 360 from 395 to get 35.
Take the next digit (2) from the dividend and append it to 35, then repeat: 352 / 72

Step 5:
The number 72 fits into 352 4 times, leaving a remainder of 64.
Put 4 as the next digit of the answer. 
Result so far: 554.0
If we subtract 288 from 352, we get 64.
Include the next digit (1) from the dividend after 64, then repeat: 641 / 72

Advancing to step 6:
When dividing 641 by 72, we get 8 with a remainder of 65.
Put 8 as the next digit of the answer. 
Result so far: 5548.0
If we take 576 away from 641, we end up with 65.
Since there are no more digits in the dividend, we add a zero to the remainder making it 650, and continue the process.

Step 7:
If we divide 650 by 72, we get 9 and a remainder of 2.
Write down 9 as next digit of the result. 
Result so far: 5548.9
Deduct 648 from 650 and we're left with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Let's proceed to step 8:
When dividing 20 by 72, we get 0 with a remainder of 20.
Write down 0 as next digit of the result. 
Result so far: 5548.9
Subtract 0 from 20 to 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.

Let's proceed to step 9:
200 divided by 72 is 2 with a remainder of 56.
The number 2 becomes the next digit in our result. 
Result so far: 5548.902
If we subtract 144 from 200, we get 56.
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 10:
560 divided by 72 is 7 with a remainder of 56.
Record the quotient 7 as the next digit in the result. 
Result so far: 5548.9027
If we subtract 504 from 560, we get 56.
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 11:
560 divided by 72 is 7 with a remainder of 56.
Write down 7 as next digit of the result. 
Result so far: 5548.90277
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.

After the division, we end up with 5548.90277 and a remainder of 5.6e-05.