We're dividing 35531604 by 999 
The aim is to understand the frequency of 999 in 35531604.

Going ahead to step 1:
999 goes into 3 0 times with a remainder of 3.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 3 leaves us with 3.
Grab the next digit (5) from the dividend, add it to 3, then carry on: 35 / 999

Moving on to step 2:
The number 999 fits into 35 0 times, leaving a remainder of 35.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 35 after subtracting 0 from 35.
Take the next digit (5) from the dividend and append it to 35, then repeat: 355 / 999

On to step 3:
999 can be fit into 355 0 times, resulting in a remainder of 355.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 355 after subtracting 0 from 355.
Append the next digit (3) from the dividend to 355 and continue with: 3553 / 999

Going ahead to step 4:
If we divide 3553 by 999, we get 3 and a remainder of 556.
The number 3 becomes the next digit in our result. 
Result so far: 3.0
Deduct 2997 from 3553 and we're left with 556.
Append the next digit (1) from the dividend to 556 and continue with: 5561 / 999

Advancing to step 5:
The number 999 fits into 5561 5 times, leaving a remainder of 566.
The next digit of our result is 5. 
Result so far: 35.0
Deduct 4995 from 5561 and we're left with 566.
Include the next digit (6) from the dividend after 566, then repeat: 5666 / 999

On to step 6:
5666 divided by 999 is 5 with a remainder of 671.
Use 5 as the next digit of our solution. 
Result so far: 355.0
Subtract 4995 from 5666 to get 671.
Grab the next digit (0) from the dividend, add it to 671, then carry on: 6710 / 999

Moving on to step 7:
999 can be fit into 6710 6 times, resulting in a remainder of 716.
The number 6 becomes the next digit in our result. 
Result so far: 3556.0
Subtract 5994 from 6710 to get 716.
Append the next digit (4) from the dividend to 716 and continue with: 7164 / 999

Step 8:
When dividing 7164 by 999, we get 7 with a remainder of 171.
Write down 7 as next digit of the result. 
Result so far: 35567.0
The remainder is 171 after subtracting 6993 from 7164.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1710, and continue the process.

Going ahead to step 9:
999 goes into 1710 1 times with a remainder of 711.
Write down 1 as next digit of the result. 
Result so far: 35567.1
The remainder is 711 after subtracting 999 from 1710.
Since there are no more digits in the dividend, we add a zero to the remainder making it 7110, and continue the process.

Step 10:
If we divide 7110 by 999, we get 7 and a remainder of 117.
Write down 7 as next digit of the result. 
Result so far: 35567.17
Subtract 6993 from 7110 to get 117.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1170, and continue the process.

Step 11:
The number 999 fits into 1170 1 times, leaving a remainder of 171.
Write down 1 as next digit of the result. 
Result so far: 35567.171
If we take 999 away from 1170, we end up with 171.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1710, and continue the process.

Moving on to step 12:
When dividing 1710 by 999, we get 1 with a remainder of 711.
Use 1 as the next digit of our solution. 
Result so far: 35567.1711
Deduct 999 from 1710 and we're left with 711.
Since there are no more digits in the dividend, we add a zero to the remainder making it 7110, and continue the process.

The final result is 35567.1711 with a remainder of 0.00711.