We look at the division of 399549 by 631 
The aim is to understand the frequency of 631 in 399549.

Advancing to step 1:
631 can be fit into 3 0 times, resulting in a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we subtract 0 from 3, we get 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 631

Going ahead to step 2:
631 goes into 39 0 times with a remainder of 39.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 39, we get 39.
Bring next digit (9) of the dividend behind the 39 and repeat the process: 399 / 631

On to step 3:
399 divided by 631 is 0 with a remainder of 399.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 399 and we're left with 399.
Grab the next digit (5) from the dividend, add it to 399, then carry on: 3995 / 631

Advancing to step 4:
3995 divided by 631 is 6 with a remainder of 209.
Write down 6 as next digit of the result. 
Result so far: 6.0
Subtract 3786 from 3995 to get 209.
Take the next digit (4) from the dividend and append it to 209, then repeat: 2094 / 631

Moving on to step 5:
2094 divided by 631 is 3 with a remainder of 201.
Write down 3 as next digit of the result. 
Result so far: 63.0
Subtract 1893 from 2094 to get 201.
Append the next digit (9) from the dividend to 201 and continue with: 2019 / 631

Advancing to step 6:
The number 631 fits into 2019 3 times, leaving a remainder of 126.
Record the quotient 3 as the next digit in the result. 
Result so far: 633.0
Subtract 1893 from 2019 to get 126.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1260, and continue the process.

Step 7:
631 can be fit into 1260 1 times, resulting in a remainder of 629.
Record the quotient 1 as the next digit in the result. 
Result so far: 633.1
Subtract 631 from 1260 to get 629.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6290, and continue the process.

Moving on to step 8:
631 can be fit into 6290 9 times, resulting in a remainder of 611.
The next digit of our result is 9. 
Result so far: 633.19
The remainder is 611 after subtracting 5679 from 6290.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6110, and continue the process.

Let's proceed to step 9:
6110 divided by 631 is 9 with a remainder of 431.
Put 9 as the next digit of the answer. 
Result so far: 633.199
Subtract 5679 from 6110 to get 431.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4310, and continue the process.

The quotient of the division is 633.199, and the remainder is 0.0431.