We're dividing 406635 by 18 
The aim is to understand the frequency of 18 in 406635.

Step 1:
The number 18 fits into 4 0 times, leaving a remainder of 4.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 4 after subtracting 0 from 4.
Include the next digit (0) from the dividend after 4, then repeat: 40 / 18

Let's proceed to step 2:
If we divide 40 by 18, we get 2 and a remainder of 4.
Write down 2 as next digit of the result. 
Result so far: 2.0
Deduct 36 from 40 and we're left with 4.
Append the next digit (6) from the dividend to 4 and continue with: 46 / 18

Let's proceed to step 3:
If we divide 46 by 18, we get 2 and a remainder of 10.
Record the quotient 2 as the next digit in the result. 
Result so far: 22.0
The remainder is 10 after subtracting 36 from 46.
Take the next digit (6) from the dividend and append it to 10, then repeat: 106 / 18

Step 4:
The number 18 fits into 106 5 times, leaving a remainder of 16.
Put 5 as the next digit of the answer. 
Result so far: 225.0
Deduct 90 from 106 and we're left with 16.
Append the next digit (3) from the dividend to 16 and continue with: 163 / 18

Advancing to step 5:
The number 18 fits into 163 9 times, leaving a remainder of 1.
Record the quotient 9 as the next digit in the result. 
Result so far: 2259.0
If we subtract 162 from 163, we get 1.
Include the next digit (5) from the dividend after 1, then repeat: 15 / 18

Step 6:
If we divide 15 by 18, we get 0 and a remainder of 15.
Put 0 as the next digit of the answer. 
Result so far: 22590.0
Subtract 0 from 15 to get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Let's proceed to step 7:
18 can be fit into 150 8 times, resulting in a remainder of 6.
Write down 8 as next digit of the result. 
Result so far: 22590.8
Subtracting 144 from 150 leaves us 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.

Step 8:
When dividing 60 by 18, we get 3 with a remainder of 6.
Record the quotient 3 as the next digit in the result. 
Result so far: 22590.83
Subtract 54 from 60 to get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Let's proceed to step 9:
When dividing 60 by 18, we get 3 with a remainder of 6.
The next digit of our result is 3. 
Result so far: 22590.833
The remainder is 6 after subtracting 54 from 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

After the division, we end up with 22590.833 and a remainder of 0.0006.