We look at the division of 65519 by 15 
The aim is to understand the frequency of 15 in 65519.

Step 1:
If we divide 6 by 15, we get 0 and a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Include the next digit (5) from the dividend after 6, then repeat: 65 / 15

On to step 2:
65 divided by 15 is 4 with a remainder of 5.
Write down 4 as next digit of the result. 
Result so far: 4.0
Subtracting 60 from 65 leaves us with 5.
Append the next digit (5) from the dividend to 5 and continue with: 55 / 15

Advancing to step 3:
15 can be fit into 55 3 times, resulting in a remainder of 10.
The number 3 becomes the next digit in our result. 
Result so far: 43.0
Subtract 45 from 55 to get 10.
Include the next digit (1) from the dividend after 10, then repeat: 101 / 15

Let's proceed to step 4:
When dividing 101 by 15, we get 6 with a remainder of 11.
Record the quotient 6 as the next digit in the result. 
Result so far: 436.0
Subtracting 90 from 101 leaves us with 11.
Append the next digit (9) from the dividend to 11 and continue with: 119 / 15

Let's proceed to step 5:
When dividing 119 by 15, we get 7 with a remainder of 14.
Use 7 as the next digit of our solution. 
Result so far: 4367.0
If we subtract 105 from 119, we get 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Step 6:
15 can be fit into 140 9 times, resulting in a remainder of 5.
The next digit of our result is 9. 
Result so far: 4367.9
If we subtract 135 from 140, 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.

Advancing to step 7:
If we divide 50 by 15, we get 3 and a remainder of 5.
Record the quotient 3 as the next digit in the result. 
Result so far: 4367.93
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.

On to step 8:
The number 15 fits into 50 3 times, leaving a remainder of 5.
The next digit of our result is 3. 
Result so far: 4367.933
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.

Our division results in 4367.933 with a remaining 0.0005.