We divide 515900 by 18
The aim is to understand the frequency of 18 in 515900.

Moving on to step 1:
If we divide 5 by 18, we get 0 and a remainder of 5.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 5 leaves us with 5.
Bring next digit (1) of the dividend behind the 5 and repeat the process: 51 / 18

On to step 2:
18 can be fit into 51 2 times, resulting in a remainder of 15.
Use 2 as the next digit of our solution. 
Result so far: 2.0
Deduct 36 from 51 and we're left with 15.
Append the next digit (5) from the dividend to 15 and continue with: 155 / 18

Advancing to step 3:
155 divided by 18 is 8 with a remainder of 11.
Use 8 as the next digit of our solution. 
Result so far: 28.0
If we subtract 144 from 155, we get 11.
Bring next digit (9) of the dividend behind the 11 and repeat the process: 119 / 18

On to step 4:
18 goes into 119 6 times with a remainder of 11.
Record the quotient 6 as the next digit in the result. 
Result so far: 286.0
The remainder is 11 after subtracting 108 from 119.
Take the next digit (0) from the dividend and append it to 11, then repeat: 110 / 18

Step 5:
The number 18 fits into 110 6 times, leaving a remainder of 2.
The next digit of our result is 6. 
Result so far: 2866.0
The remainder is 2 after subtracting 108 from 110.
Grab the next digit (0) from the dividend, add it to 2, then carry on: 20 / 18

Let's proceed to step 6:
20 divided by 18 is 1 with a remainder of 2.
Put 1 as the next digit of the answer. 
Result so far: 28661.0
If we subtract 18 from 20, we get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Step 7:
18 goes into 20 1 times with a remainder of 2.
The number 1 becomes the next digit in our result. 
Result so far: 28661.1
Subtract 18 from 20 to get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Step 8:
18 goes into 20 1 times with a remainder of 2.
The number 1 becomes the next digit in our result. 
Result so far: 28661.11
Subtract 18 from 20 to get 2.
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 result is 28661.11 with a remainder of 0.002.