We look at the division of 800405 by 15 
The aim is to understand the frequency of 15 in 800405.

Going ahead to step 1:
15 goes into 8 0 times with a remainder of 8.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 8 after subtracting 0 from 8.
Include the next digit (0) from the dividend after 8, then repeat: 80 / 15

Let's proceed to step 2:
15 can be fit into 80 5 times, resulting in a remainder of 5.
Record the quotient 5 as the next digit in the result. 
Result so far: 5.0
Subtract 75 from 80 to get 5.
Include the next digit (0) from the dividend after 5, then repeat: 50 / 15

On to step 3:
When dividing 50 by 15, we get 3 with a remainder of 5.
Record the quotient 3 as the next digit in the result. 
Result so far: 53.0
Deduct 45 from 50 and we're left with 5.
Take the next digit (4) from the dividend and append it to 5, then repeat: 54 / 15

Advancing to step 4:
The number 15 fits into 54 3 times, leaving a remainder of 9.
Use 3 as the next digit of our solution. 
Result so far: 533.0
If we take 45 away from 54, we end up with 9.
Bring next digit (0) of the dividend behind the 9 and repeat the process: 90 / 15

Advancing to step 5:
The number 15 fits into 90 6 times, leaving a remainder of 0.
Write down 6 as next digit of the result. 
Result so far: 5336.0
Subtracting 90 from 90 leaves us with 0.
Include the next digit (5) from the dividend after 0, then repeat: 5 / 15

Advancing to step 6:
When dividing 5 by 15, we get 0 with a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 53360.0
If we take 0 away from 5, we end up with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

On to step 7:
When dividing 50 by 15, we get 3 with a remainder of 5.
Use 3 as the next digit of our solution. 
Result so far: 53360.3
If we subtract 45 from 50, we get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Step 8:
15 can be fit into 50 3 times, resulting in a remainder of 5.
The number 3 becomes the next digit in our result. 
Result so far: 53360.33
Subtracting 45 from 50 leaves us with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

The quotient of the division is 53360.33, and the remainder is 0.005.