28603952 ÷ 399 
The aim is to understand the frequency of 399 in 28603952.

Moving on to step 1:
399 goes into 2 0 times with a remainder of 2.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 2, we get 2.
Take the next digit (8) from the dividend and append it to 2, then repeat: 28 / 399

Let's proceed to step 2:
The number 399 fits into 28 0 times, leaving a remainder of 28.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 28 and we're left with 28.
Bring next digit (6) of the dividend behind the 28 and repeat the process: 286 / 399

Moving on to step 3:
If we divide 286 by 399, we get 0 and a remainder of 286.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 286, we get 286.
Grab the next digit (0) from the dividend, add it to 286, then carry on: 2860 / 399

Let's proceed to step 4:
399 can be fit into 2860 7 times, resulting in a remainder of 67.
The number 7 becomes the next digit in our result. 
Result so far: 7.0
If we take 2793 away from 2860, we end up with 67.
Bring next digit (3) of the dividend behind the 67 and repeat the process: 673 / 399

Advancing to step 5:
If we divide 673 by 399, we get 1 and a remainder of 274.
The next digit of our result is 1. 
Result so far: 71.0
Deduct 399 from 673 and we're left with 274.
Fetch the next digit (9) from the dividend, attach it to 274 and continue: 2749 / 399

Step 6:
2749 divided by 399 is 6 with a remainder of 355.
Record the quotient 6 as the next digit in the result. 
Result so far: 716.0
If we subtract 2394 from 2749, we get 355.
Append the next digit (5) from the dividend to 355 and continue with: 3555 / 399

Going ahead to step 7:
When dividing 3555 by 399, we get 8 with a remainder of 363.
The number 8 becomes the next digit in our result. 
Result so far: 7168.0
Subtracting 3192 from 3555 leaves us with 363.
Include the next digit (2) from the dividend after 363, then repeat: 3632 / 399

Going ahead to step 8:
The number 399 fits into 3632 9 times, leaving a remainder of 41.
Use 9 as the next digit of our solution. 
Result so far: 71689.0
If we take 3591 away from 3632, we end up with 41.
Since there are no more digits in the dividend, we add a zero to the remainder making it 410, and continue the process.

Advancing to step 9:
The number 399 fits into 410 1 times, leaving a remainder of 11.
Record the quotient 1 as the next digit in the result. 
Result so far: 71689.1
The remainder is 11 after subtracting 399 from 410.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Moving on to step 10:
The number 399 fits into 110 0 times, leaving a remainder of 110.
Use 0 as the next digit of our solution. 
Result so far: 71689.1
Subtracting 0 from 110 leaves us with 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1100, and continue the process.

Moving on to step 11:
If we divide 1100 by 399, we get 2 and a remainder of 302.
Put 2 as the next digit of the answer. 
Result so far: 71689.102
Subtracting 798 from 1100 leaves us with 302.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3020, and continue the process.

Advancing to step 12:
If we divide 3020 by 399, we get 7 and a remainder of 227.
The number 7 becomes the next digit in our result. 
Result so far: 71689.1027
Deduct 2793 from 3020 and we're left with 227.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2270, and continue the process.

Going ahead to step 13:
If we divide 2270 by 399, we get 5 and a remainder of 275.
The number 5 becomes the next digit in our result. 
Result so far: 71689.10275
The remainder is 275 after subtracting 1995 from 2270.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2750, and continue the process.

Let's proceed to step 14:
If we divide 2750 by 399, we get 6 and a remainder of 356.
Write down 6 as next digit of the result. 
Result so far: 71689.102756
If we subtract 2394 from 2750, we get 356.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3560, and continue the process.

On to step 15:
399 goes into 3560 8 times with a remainder of 368.
Record the quotient 8 as the next digit in the result. 
Result so far: 71689.1027568
If we subtract 3192 from 3560, we get 368.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3680, and continue the process.

Going ahead to step 16:
If we divide 3680 by 399, we get 9 and a remainder of 89.
Record the quotient 9 as the next digit in the result. 
Result so far: 71689.10275689
Subtracting 3591 from 3680 leaves us with 89.
Since there are no more digits in the dividend, we add a zero to the remainder making it 890, and continue the process.

In conclusion, the division gives 71689.10275689 with a balance of 8.9e-08.