We look at the division of 396566 by 3 
The aim is to understand the frequency of 3 in 396566.

Step 1:
The number 3 fits into 3 1 times, leaving a remainder of 0.
Write down 1 as next digit of the result. 
Result so far: 1.0
Deduct 3 from 3 and we're left with 0.
Include the next digit (9) from the dividend after 0, then repeat: 9 / 3

Step 2:
When dividing 9 by 3, we get 3 with a remainder of 0.
Put 3 as the next digit of the answer. 
Result so far: 13.0
Deduct 9 from 9 and we're left with 0.
Grab the next digit (6) from the dividend, add it to 0, then carry on: 6 / 3

Advancing to step 3:
6 divided by 3 is 2 with a remainder of 0.
Put 2 as the next digit of the answer. 
Result so far: 132.0
If we take 6 away from 6, we end up with 0.
Grab the next digit (5) from the dividend, add it to 0, then carry on: 5 / 3

Step 4:
The number 3 fits into 5 1 times, leaving a remainder of 2.
The next digit of our result is 1. 
Result so far: 1321.0
If we take 3 away from 5, we end up with 2.
Append the next digit (6) from the dividend to 2 and continue with: 26 / 3

Moving on to step 5:
3 goes into 26 8 times with a remainder of 2.
Use 8 as the next digit of our solution. 
Result so far: 13218.0
The remainder is 2 after subtracting 24 from 26.
Include the next digit (6) from the dividend after 2, then repeat: 26 / 3

Step 6:
If we divide 26 by 3, we get 8 and a remainder of 2.
The next digit of our result is 8. 
Result so far: 132188.0
If we take 24 away from 26, 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.

On to step 7:
3 goes into 20 6 times with a remainder of 2.
Record the quotient 6 as the next digit in the result. 
Result so far: 132188.6
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.

On to step 8:
If we divide 20 by 3, we get 6 and a remainder of 2.
Record the quotient 6 as the next digit in the result. 
Result so far: 132188.66
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 132188.66, with a leftover of 0.002.