35972868 divided by 399 
The aim is to understand the frequency of 399 in 35972868.

Advancing to step 1:
399 goes into 3 0 times with a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we subtract 0 from 3, we get 3.
Take the next digit (5) from the dividend and append it to 3, then repeat: 35 / 399

Let's proceed to step 2:
399 can be fit into 35 0 times, resulting in a remainder of 35.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 35, we end up with 35.
Take the next digit (9) from the dividend and append it to 35, then repeat: 359 / 399

Step 3:
399 can be fit into 359 0 times, resulting in a remainder of 359.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 359 to get 359.
Bring next digit (7) of the dividend behind the 359 and repeat the process: 3597 / 399

Step 4:
3597 divided by 399 is 9 with a remainder of 6.
Record the quotient 9 as the next digit in the result. 
Result so far: 9.0
Deduct 3591 from 3597 and we're left with 6.
Append the next digit (2) from the dividend to 6 and continue with: 62 / 399

On to step 5:
62 divided by 399 is 0 with a remainder of 62.
Write down 0 as next digit of the result. 
Result so far: 90.0
Subtracting 0 from 62 leaves us with 62.
Take the next digit (8) from the dividend and append it to 62, then repeat: 628 / 399

On to step 6:
When dividing 628 by 399, we get 1 with a remainder of 229.
The number 1 becomes the next digit in our result. 
Result so far: 901.0
Deduct 399 from 628 and we're left with 229.
Take the next digit (6) from the dividend and append it to 229, then repeat: 2296 / 399

Going ahead to step 7:
399 can be fit into 2296 5 times, resulting in a remainder of 301.
Record the quotient 5 as the next digit in the result. 
Result so far: 9015.0
Deduct 1995 from 2296 and we're left with 301.
Grab the next digit (8) from the dividend, add it to 301, then carry on: 3018 / 399

Let's proceed to step 8:
If we divide 3018 by 399, we get 7 and a remainder of 225.
The next digit of our result is 7. 
Result so far: 90157.0
The remainder is 225 after subtracting 2793 from 3018.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2250, and continue the process.

Let's proceed to step 9:
2250 divided by 399 is 5 with a remainder of 255.
The next digit of our result is 5. 
Result so far: 90157.5
Deduct 1995 from 2250 and we're left with 255.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2550, and continue the process.

On to step 10:
The number 399 fits into 2550 6 times, leaving a remainder of 156.
Write down 6 as next digit of the result. 
Result so far: 90157.56
Deduct 2394 from 2550 and we're left with 156.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1560, and continue the process.

Moving on to step 11:
If we divide 1560 by 399, we get 3 and a remainder of 363.
Put 3 as the next digit of the answer. 
Result so far: 90157.563
The remainder is 363 after subtracting 1197 from 1560.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3630, and continue the process.

Advancing to step 12:
The number 399 fits into 3630 9 times, leaving a remainder of 39.
Record the quotient 9 as the next digit in the result. 
Result so far: 90157.5639
Subtract 3591 from 3630 to get 39.
Since there are no more digits in the dividend, we add a zero to the remainder making it 390, and continue the process.

Going ahead to step 13:
The number 399 fits into 390 0 times, leaving a remainder of 390.
Write down 0 as next digit of the result. 
Result so far: 90157.5639
Subtract 0 from 390 to get 390.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3900, and continue the process.

Moving on to step 14:
If we divide 3900 by 399, we get 9 and a remainder of 309.
Use 9 as the next digit of our solution. 
Result so far: 90157.563909
If we take 3591 away from 3900, we end up with 309.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3090, and continue the process.

Step 15:
The number 399 fits into 3090 7 times, leaving a remainder of 297.
The next digit of our result is 7. 
Result so far: 90157.5639097
Deduct 2793 from 3090 and we're left with 297.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2970, and continue the process.

Let's proceed to step 16:
399 can be fit into 2970 7 times, resulting in a remainder of 177.
Put 7 as the next digit of the answer. 
Result so far: 90157.56390977
Subtract 2793 from 2970 to get 177.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1770, and continue the process.

The final outcome is 90157.56390977, with a leftover of 1.77e-07.