519191 ÷ 3 
The aim is to understand the frequency of 3 in 519191.

Let's proceed to step 1:
If we divide 5 by 3, we get 1 and a remainder of 2.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
Subtracting 3 from 5 leaves us with 2.
Grab the next digit (1) from the dividend, add it to 2, then carry on: 21 / 3

Advancing to step 2:
If we divide 21 by 3, we get 7 and a remainder of 0.
The next digit of our result is 7. 
Result so far: 17.0
If we take 21 away from 21, we end up with 0.
Include the next digit (9) from the dividend after 0, then repeat: 9 / 3

Advancing to step 3:
3 goes into 9 3 times with a remainder of 0.
The number 3 becomes the next digit in our result. 
Result so far: 173.0
Subtracting 9 from 9 leaves us with 0.
Take the next digit (1) from the dividend and append it to 0, then repeat: 1 / 3

Moving on to step 4:
When dividing 1 by 3, we get 0 with a remainder of 1.
The number 0 becomes the next digit in our result. 
Result so far: 1730.0
If we take 0 away from 1, we end up with 1.
Take the next digit (9) from the dividend and append it to 1, then repeat: 19 / 3

Moving on to step 5:
The number 3 fits into 19 6 times, leaving a remainder of 1.
Write down 6 as next digit of the result. 
Result so far: 17306.0
Subtracting 18 from 19 leaves us with 1.
Take the next digit (1) from the dividend and append it to 1, then repeat: 11 / 3

Moving on to step 6:
If we divide 11 by 3, we get 3 and a remainder of 2.
The number 3 becomes the next digit in our result. 
Result so far: 173063.0
Deduct 9 from 11 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.

Going ahead to step 7:
When dividing 20 by 3, we get 6 with a remainder of 2.
Put 6 as the next digit of the answer. 
Result so far: 173063.6
If we take 18 away from 20, we end up 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.

Advancing to step 8:
When dividing 20 by 3, we get 6 with a remainder of 2.
Use 6 as the next digit of our solution. 
Result so far: 173063.66
The remainder is 2 after subtracting 18 from 20.
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 173063.66, with a leftover of 0.002.