643529 divided by 75 
The aim is to understand the frequency of 75 in 643529.

Step 1:
6 divided by 75 is 0 with a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Include the next digit (4) from the dividend after 6, then repeat: 64 / 75

On to step 2:
The number 75 fits into 64 0 times, leaving a remainder of 64.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 64 to get 64.
Fetch the next digit (3) from the dividend, attach it to 64 and continue: 643 / 75

Moving on to step 3:
643 divided by 75 is 8 with a remainder of 43.
The next digit of our result is 8. 
Result so far: 8.0
The remainder is 43 after subtracting 600 from 643.
Include the next digit (5) from the dividend after 43, then repeat: 435 / 75

Going ahead to step 4:
435 divided by 75 is 5 with a remainder of 60.
Put 5 as the next digit of the answer. 
Result so far: 85.0
If we subtract 375 from 435, we get 60.
Grab the next digit (2) from the dividend, add it to 60, then carry on: 602 / 75

Advancing to step 5:
The number 75 fits into 602 8 times, leaving a remainder of 2.
The next digit of our result is 8. 
Result so far: 858.0
If we subtract 600 from 602, we get 2.
Append the next digit (9) from the dividend to 2 and continue with: 29 / 75

Moving on to step 6:
29 divided by 75 is 0 with a remainder of 29.
Put 0 as the next digit of the answer. 
Result so far: 8580.0
Subtracting 0 from 29 leaves us with 29.
Since there are no more digits in the dividend, we add a zero to the remainder making it 290, and continue the process.

Step 7:
75 can be fit into 290 3 times, resulting in a remainder of 65.
Put 3 as the next digit of the answer. 
Result so far: 8580.3
Subtract 225 from 290 to get 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 8:
650 divided by 75 is 8 with a remainder of 50.
Record the quotient 8 as the next digit in the result. 
Result so far: 8580.38
If we subtract 600 from 650, we get 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

On to step 9:
If we divide 500 by 75, we get 6 and a remainder of 50.
Put 6 as the next digit of the answer. 
Result so far: 8580.386
The remainder is 50 after subtracting 450 from 500.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

Let's proceed to step 10:
If we divide 500 by 75, we get 6 and a remainder of 50.
Record the quotient 6 as the next digit in the result. 
Result so far: 8580.3866
If we take 450 away from 500, we end up with 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

The final outcome is 8580.3866, with a leftover of 0.0005.