We look at the division of 686931 by 18 
The aim is to understand the frequency of 18 in 686931.

Step 1:
18 can be fit into 6 0 times, resulting in a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Fetch the next digit (8) from the dividend, attach it to 6 and continue: 68 / 18

Step 2:
The number 18 fits into 68 3 times, leaving a remainder of 14.
The next digit of our result is 3. 
Result so far: 3.0
The remainder is 14 after subtracting 54 from 68.
Append the next digit (6) from the dividend to 14 and continue with: 146 / 18

Let's proceed to step 3:
If we divide 146 by 18, we get 8 and a remainder of 2.
The next digit of our result is 8. 
Result so far: 38.0
Subtract 144 from 146 to get 2.
Bring next digit (9) of the dividend behind the 2 and repeat the process: 29 / 18

Moving on to step 4:
The number 18 fits into 29 1 times, leaving a remainder of 11.
The number 1 becomes the next digit in our result. 
Result so far: 381.0
If we take 18 away from 29, we end up with 11.
Grab the next digit (3) from the dividend, add it to 11, then carry on: 113 / 18

Step 5:
If we divide 113 by 18, we get 6 and a remainder of 5.
Write down 6 as next digit of the result. 
Result so far: 3816.0
Deduct 108 from 113 and we're left with 5.
Include the next digit (1) from the dividend after 5, then repeat: 51 / 18

Moving on to step 6:
18 goes into 51 2 times with a remainder of 15.
The number 2 becomes the next digit in our result. 
Result so far: 38162.0
The remainder is 15 after subtracting 36 from 51.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Advancing to step 7:
18 goes into 150 8 times with a remainder of 6.
Put 8 as the next digit of the answer. 
Result so far: 38162.8
The remainder is 6 after subtracting 144 from 150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Advancing to step 8:
The number 18 fits into 60 3 times, leaving a remainder of 6.
Use 3 as the next digit of our solution. 
Result so far: 38162.83
Deduct 54 from 60 and we're left with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Going ahead to step 9:
The number 18 fits into 60 3 times, leaving a remainder of 6.
The number 3 becomes the next digit in our result. 
Result so far: 38162.833
If we take 54 away from 60, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

The final outcome is 38162.833, with a leftover of 0.0006.