We divide 509843 by 3
The aim is to understand the frequency of 3 in 509843.

Going ahead to step 1:
3 can be fit into 5 1 times, resulting in a remainder of 2.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Subtracting 3 from 5 leaves us with 2.
Fetch the next digit (0) from the dividend, attach it to 2 and continue: 20 / 3

Moving on to step 2:
20 divided by 3 is 6 with a remainder of 2.
Use 6 as the next digit of our solution. 
Result so far: 16.0
If we subtract 18 from 20, we get 2.
Include the next digit (9) from the dividend after 2, then repeat: 29 / 3

Moving on to step 3:
When dividing 29 by 3, we get 9 with a remainder of 2.
Use 9 as the next digit of our solution. 
Result so far: 169.0
The remainder is 2 after subtracting 27 from 29.
Grab the next digit (8) from the dividend, add it to 2, then carry on: 28 / 3

Step 4:
3 can be fit into 28 9 times, resulting in a remainder of 1.
Write down 9 as next digit of the result. 
Result so far: 1699.0
Deduct 27 from 28 and we're left with 1.
Append the next digit (4) from the dividend to 1 and continue with: 14 / 3

Step 5:
If we divide 14 by 3, we get 4 and a remainder of 2.
Put 4 as the next digit of the answer. 
Result so far: 16994.0
If we subtract 12 from 14, we get 2.
Bring next digit (3) of the dividend behind the 2 and repeat the process: 23 / 3

Moving on to step 6:
When dividing 23 by 3, we get 7 with a remainder of 2.
The next digit of our result is 7. 
Result so far: 169947.0
If we subtract 21 from 23, we get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Let's proceed to step 7:
3 goes into 20 6 times with a remainder of 2.
Write down 6 as next digit of the result. 
Result so far: 169947.6
Deduct 18 from 20 and we're left with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

On to step 8:
3 can be fit into 20 6 times, resulting in a remainder of 2.
The next digit of our result is 6. 
Result so far: 169947.66
Subtracting 18 from 20 leaves us with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

The final outcome is 169947.66, with a leftover of 0.002.