We're dividing 851591 by 43 
The aim is to understand the frequency of 43 in 851591.

Step 1:
When dividing 8 by 43, we get 0 with a remainder of 8.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 8 after subtracting 0 from 8.
Include the next digit (5) from the dividend after 8, then repeat: 85 / 43

Step 2:
43 can be fit into 85 1 times, resulting in a remainder of 42.
Put 1 as the next digit of the answer. 
Result so far: 1.0
Subtracting 43 from 85 leaves us with 42.
Append the next digit (1) from the dividend to 42 and continue with: 421 / 43

Step 3:
If we divide 421 by 43, we get 9 and a remainder of 34.
The next digit of our result is 9. 
Result so far: 19.0
Subtracting 387 from 421 leaves us with 34.
Take the next digit (5) from the dividend and append it to 34, then repeat: 345 / 43

Advancing to step 4:
When dividing 345 by 43, we get 8 with a remainder of 1.
Record the quotient 8 as the next digit in the result. 
Result so far: 198.0
If we take 344 away from 345, we end up with 1.
Grab the next digit (9) from the dividend, add it to 1, then carry on: 19 / 43

Moving on to step 5:
The number 43 fits into 19 0 times, leaving a remainder of 19.
Put 0 as the next digit of the answer. 
Result so far: 1980.0
Subtract 0 from 19 to get 19.
Fetch the next digit (1) from the dividend, attach it to 19 and continue: 191 / 43

Let's proceed to step 6:
When dividing 191 by 43, we get 4 with a remainder of 19.
The next digit of our result is 4. 
Result so far: 19804.0
The remainder is 19 after subtracting 172 from 191.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Step 7:
If we divide 190 by 43, we get 4 and a remainder of 18.
The next digit of our result is 4. 
Result so far: 19804.4
If we subtract 172 from 190, we get 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

On to step 8:
When dividing 180 by 43, we get 4 with a remainder of 8.
Put 4 as the next digit of the answer. 
Result so far: 19804.44
If we take 172 away from 180, we end up with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

The quotient of the division is 19804.44, and the remainder is 0.008.