843871 ÷ 42 
The aim is to understand the frequency of 42 in 843871.

Advancing to step 1:
8 divided by 42 is 0 with a remainder of 8.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 8 and we're left with 8.
Take the next digit (4) from the dividend and append it to 8, then repeat: 84 / 42

Let's proceed to step 2:
If we divide 84 by 42, we get 2 and a remainder of 0.
Put 2 as the next digit of the answer. 
Result so far: 2.0
The remainder is 0 after subtracting 84 from 84.
Append the next digit (3) from the dividend to 0 and continue with: 3 / 42

Moving on to step 3:
42 can be fit into 3 0 times, resulting in a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 20.0
The remainder is 3 after subtracting 0 from 3.
Bring next digit (8) of the dividend behind the 3 and repeat the process: 38 / 42

Moving on to step 4:
42 can be fit into 38 0 times, resulting in a remainder of 38.
The number 0 becomes the next digit in our result. 
Result so far: 200.0
If we take 0 away from 38, we end up with 38.
Take the next digit (7) from the dividend and append it to 38, then repeat: 387 / 42

Let's proceed to step 5:
If we divide 387 by 42, we get 9 and a remainder of 9.
Put 9 as the next digit of the answer. 
Result so far: 2009.0
Subtract 378 from 387 to get 9.
Grab the next digit (1) from the dividend, add it to 9, then carry on: 91 / 42

Going ahead to step 6:
When dividing 91 by 42, we get 2 with a remainder of 7.
Use 2 as the next digit of our solution. 
Result so far: 20092.0
Deduct 84 from 91 and we're left with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

On to step 7:
70 divided by 42 is 1 with a remainder of 28.
The number 1 becomes the next digit in our result. 
Result so far: 20092.1
Subtract 42 from 70 to get 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

Moving on to step 8:
The number 42 fits into 280 6 times, leaving a remainder of 28.
Record the quotient 6 as the next digit in the result. 
Result so far: 20092.16
If we take 252 away from 280, we end up with 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

Moving on to step 9:
If we divide 280 by 42, we get 6 and a remainder of 28.
The next digit of our result is 6. 
Result so far: 20092.166
The remainder is 28 after subtracting 252 from 280.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

After the division, we end up with 20092.166 and a remainder of 0.0028.