We look at the division of 809578 by 18 
The aim is to understand the frequency of 18 in 809578.

Step 1:
18 goes into 8 0 times with a remainder of 8.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 8 to get 8.
Fetch the next digit (0) from the dividend, attach it to 8 and continue: 80 / 18

Step 2:
18 can be fit into 80 4 times, resulting in a remainder of 8.
The number 4 becomes the next digit in our result. 
Result so far: 4.0
The remainder is 8 after subtracting 72 from 80.
Bring next digit (9) of the dividend behind the 8 and repeat the process: 89 / 18

On to step 3:
The number 18 fits into 89 4 times, leaving a remainder of 17.
The next digit of our result is 4. 
Result so far: 44.0
If we take 72 away from 89, we end up with 17.
Fetch the next digit (5) from the dividend, attach it to 17 and continue: 175 / 18

Advancing to step 4:
175 divided by 18 is 9 with a remainder of 13.
The number 9 becomes the next digit in our result. 
Result so far: 449.0
Subtracting 162 from 175 leaves us with 13.
Include the next digit (7) from the dividend after 13, then repeat: 137 / 18

Step 5:
The number 18 fits into 137 7 times, leaving a remainder of 11.
The next digit of our result is 7. 
Result so far: 4497.0
Subtracting 126 from 137 leaves us with 11.
Append the next digit (8) from the dividend to 11 and continue with: 118 / 18

Going ahead to step 6:
118 divided by 18 is 6 with a remainder of 10.
Record the quotient 6 as the next digit in the result. 
Result so far: 44976.0
Deduct 108 from 118 and we're left with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Advancing to step 7:
18 goes into 100 5 times with a remainder of 10.
Write down 5 as next digit of the result. 
Result so far: 44976.5
If we take 90 away from 100, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Advancing to step 8:
If we divide 100 by 18, we get 5 and a remainder of 10.
The number 5 becomes the next digit in our result. 
Result so far: 44976.55
If we subtract 90 from 100, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

The quotient of the division is 44976.55, and the remainder is 0.01.