We look at the division of 507775 by 15 
The aim is to understand the frequency of 15 in 507775.

Step 1:
The number 15 fits into 5 0 times, leaving a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Include the next digit (0) from the dividend after 5, then repeat: 50 / 15

On to step 2:
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: 3.0
Subtract 45 from 50 to get 5.
Append the next digit (7) from the dividend to 5 and continue with: 57 / 15

Advancing to step 3:
15 goes into 57 3 times with a remainder of 12.
The number 3 becomes the next digit in our result. 
Result so far: 33.0
The remainder is 12 after subtracting 45 from 57.
Take the next digit (7) from the dividend and append it to 12, then repeat: 127 / 15

Going ahead to step 4:
15 goes into 127 8 times with a remainder of 7.
Record the quotient 8 as the next digit in the result. 
Result so far: 338.0
If we subtract 120 from 127, we get 7.
Take the next digit (7) from the dividend and append it to 7, then repeat: 77 / 15

On to step 5:
If we divide 77 by 15, we get 5 and a remainder of 2.
Write down 5 as next digit of the result. 
Result so far: 3385.0
Subtract 75 from 77 to get 2.
Include the next digit (5) from the dividend after 2, then repeat: 25 / 15

Let's proceed to step 6:
25 divided by 15 is 1 with a remainder of 10.
The next digit of our result is 1. 
Result so far: 33851.0
The remainder is 10 after subtracting 15 from 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Let's proceed to step 7:
15 can be fit into 100 6 times, resulting in a remainder of 10.
The number 6 becomes the next digit in our result. 
Result so far: 33851.6
Subtracting 90 from 100 leaves us 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.

Going ahead to step 8:
15 can be fit into 100 6 times, resulting in a remainder of 10.
Write down 6 as next digit of the result. 
Result so far: 33851.66
Deduct 90 from 100 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.

The final result is 33851.66 with a remainder of 0.01.