We look at the division of 812500 by 3 
The aim is to understand the frequency of 3 in 812500.

Step 1:
3 goes into 8 2 times with a remainder of 2.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
Subtract 6 from 8 to get 2.
Fetch the next digit (1) from the dividend, attach it to 2 and continue: 21 / 3

Going ahead to step 2:
When dividing 21 by 3, we get 7 with a remainder of 0.
Record the quotient 7 as the next digit in the result. 
Result so far: 27.0
If we subtract 21 from 21, we get 0.
Include the next digit (2) from the dividend after 0, then repeat: 2 / 3

Moving on to step 3:
2 divided by 3 is 0 with a remainder of 2.
The next digit of our result is 0. 
Result so far: 270.0
If we take 0 away from 2, we end up with 2.
Bring next digit (5) of the dividend behind the 2 and repeat the process: 25 / 3

Advancing to step 4:
When dividing 25 by 3, we get 8 with a remainder of 1.
The next digit of our result is 8. 
Result so far: 2708.0
Subtracting 24 from 25 leaves us with 1.
Append the next digit (0) from the dividend to 1 and continue with: 10 / 3

Moving on to step 5:
If we divide 10 by 3, we get 3 and a remainder of 1.
Put 3 as the next digit of the answer. 
Result so far: 27083.0
The remainder is 1 after subtracting 9 from 10.
Take the next digit (0) from the dividend and append it to 1, then repeat: 10 / 3

Step 6:
3 goes into 10 3 times with a remainder of 1.
Use 3 as the next digit of our solution. 
Result so far: 270833.0
Subtracting 9 from 10 leaves us with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Moving on to step 7:
3 can be fit into 10 3 times, resulting in a remainder of 1.
Use 3 as the next digit of our solution. 
Result so far: 270833.3
Subtracting 9 from 10 leaves us with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

On to step 8:
The number 3 fits into 10 3 times, leaving a remainder of 1.
Use 3 as the next digit of our solution. 
Result so far: 270833.33
If we take 9 away from 10, we end up with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

The final outcome is 270833.33, with a leftover of 0.001.