Let's divide 639031 by 3
The aim is to understand the frequency of 3 in 639031.

On to step 1:
6 divided by 3 is 2 with a remainder of 0.
Put 2 as the next digit of the answer. 
Result so far: 2.0
If we subtract 6 from 6, we get 0.
Append the next digit (3) from the dividend to 0 and continue with: 3 / 3

Going ahead to step 2:
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: 21.0
If we take 3 away from 3, we end up with 0.
Take the next digit (9) from the dividend and append it to 0, then repeat: 9 / 3

On to step 3:
3 goes into 9 3 times with a remainder of 0.
Record the quotient 3 as the next digit in the result. 
Result so far: 213.0
If we subtract 9 from 9, we get 0.
Grab the next digit (0) from the dividend, add it to 0, then carry on: 0 / 3

On to step 4:
3 can be fit into 0 0 times, resulting in a remainder of 0.
The next digit of our result is 0. 
Result so far: 2130.0
If we take 0 away from 0, we end up with 0.
Bring next digit (3) of the dividend behind the 0 and repeat the process: 3 / 3

Moving on to step 5:
If we divide 3 by 3, we get 1 and a remainder of 0.
Use 1 as the next digit of our solution. 
Result so far: 21301.0
Deduct 3 from 3 and we're left with 0.
Append the next digit (1) from the dividend to 0 and continue with: 1 / 3

Moving on to step 6:
3 can be fit into 1 0 times, resulting in a remainder of 1.
The number 0 becomes the next digit in our result. 
Result so far: 213010.0
The remainder is 1 after subtracting 0 from 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 7:
3 can be fit into 10 3 times, resulting in a remainder of 1.
Write down 3 as next digit of the result. 
Result so far: 213010.3
The remainder is 1 after subtracting 9 from 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Step 8:
The number 3 fits into 10 3 times, leaving a remainder of 1.
The next digit of our result is 3. 
Result so far: 213010.33
Subtract 9 from 10 to get 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 result is 213010.33 with a remainder of 0.001.