We're dividing 52813971 by 399 
The aim is to understand the frequency of 399 in 52813971.

Step 1:
399 can be fit into 5 0 times, resulting in a remainder of 5.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Take the next digit (2) from the dividend and append it to 5, then repeat: 52 / 399

Step 2:
When dividing 52 by 399, we get 0 with a remainder of 52.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 52 and we're left with 52.
Bring next digit (8) of the dividend behind the 52 and repeat the process: 528 / 399

Moving on to step 3:
If we divide 528 by 399, we get 1 and a remainder of 129.
Write down 1 as next digit of the result. 
Result so far: 1.0
Deduct 399 from 528 and we're left with 129.
Fetch the next digit (1) from the dividend, attach it to 129 and continue: 1291 / 399

Going ahead to step 4:
When dividing 1291 by 399, we get 3 with a remainder of 94.
Put 3 as the next digit of the answer. 
Result so far: 13.0
If we subtract 1197 from 1291, we get 94.
Bring next digit (3) of the dividend behind the 94 and repeat the process: 943 / 399

Going ahead to step 5:
399 goes into 943 2 times with a remainder of 145.
Use 2 as the next digit of our solution. 
Result so far: 132.0
Deduct 798 from 943 and we're left with 145.
Include the next digit (9) from the dividend after 145, then repeat: 1459 / 399

On to step 6:
When dividing 1459 by 399, we get 3 with a remainder of 262.
The number 3 becomes the next digit in our result. 
Result so far: 1323.0
If we subtract 1197 from 1459, we get 262.
Append the next digit (7) from the dividend to 262 and continue with: 2627 / 399

Let's proceed to step 7:
399 can be fit into 2627 6 times, resulting in a remainder of 233.
Put 6 as the next digit of the answer. 
Result so far: 13236.0
Deduct 2394 from 2627 and we're left with 233.
Grab the next digit (1) from the dividend, add it to 233, then carry on: 2331 / 399

On to step 8:
2331 divided by 399 is 5 with a remainder of 336.
The number 5 becomes the next digit in our result. 
Result so far: 132365.0
If we take 1995 away from 2331, we end up with 336.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3360, and continue the process.

Advancing to step 9:
The number 399 fits into 3360 8 times, leaving a remainder of 168.
The number 8 becomes the next digit in our result. 
Result so far: 132365.8
If we take 3192 away from 3360, we end up with 168.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1680, and continue the process.

Let's proceed to step 10:
1680 divided by 399 is 4 with a remainder of 84.
Write down 4 as next digit of the result. 
Result so far: 132365.84
Subtract 1596 from 1680 to get 84.
Since there are no more digits in the dividend, we add a zero to the remainder making it 840, and continue the process.

On to step 11:
399 goes into 840 2 times with a remainder of 42.
Write down 2 as next digit of the result. 
Result so far: 132365.842
If we subtract 798 from 840, we get 42.
Since there are no more digits in the dividend, we add a zero to the remainder making it 420, and continue the process.

Step 12:
If we divide 420 by 399, we get 1 and a remainder of 21.
The number 1 becomes the next digit in our result. 
Result so far: 132365.8421
The remainder is 21 after subtracting 399 from 420.
Since there are no more digits in the dividend, we add a zero to the remainder making it 210, and continue the process.

Let's proceed to step 13:
If we divide 210 by 399, we get 0 and a remainder of 210.
The number 0 becomes the next digit in our result. 
Result so far: 132365.8421
The remainder is 210 after subtracting 0 from 210.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2100, and continue the process.

Moving on to step 14:
399 can be fit into 2100 5 times, resulting in a remainder of 105.
Use 5 as the next digit of our solution. 
Result so far: 132365.842105
Deduct 1995 from 2100 and we're left with 105.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1050, and continue the process.

Let's proceed to step 15:
If we divide 1050 by 399, we get 2 and a remainder of 252.
Use 2 as the next digit of our solution. 
Result so far: 132365.8421052
If we take 798 away from 1050, we end up with 252.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2520, and continue the process.

Step 16:
399 can be fit into 2520 6 times, resulting in a remainder of 126.
Record the quotient 6 as the next digit in the result. 
Result so far: 132365.84210526
Deduct 2394 from 2520 and we're left with 126.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1260, and continue the process.

In conclusion, the division gives 132365.84210526 with a balance of 1.26e-07.