578975 ÷ 15 
The aim is to understand the frequency of 15 in 578975.

Step 1:
The number 15 fits into 5 0 times, leaving a remainder of 5.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 5 leaves us with 5.
Fetch the next digit (7) from the dividend, attach it to 5 and continue: 57 / 15

Moving on to step 2:
15 goes into 57 3 times with a remainder of 12.
The next digit of our result is 3. 
Result so far: 3.0
If we take 45 away from 57, we end up with 12.
Bring next digit (8) of the dividend behind the 12 and repeat the process: 128 / 15

Moving on to step 3:
15 can be fit into 128 8 times, resulting in a remainder of 8.
The number 8 becomes the next digit in our result. 
Result so far: 38.0
Deduct 120 from 128 and we're left with 8.
Append the next digit (9) from the dividend to 8 and continue with: 89 / 15

Going ahead to step 4:
15 goes into 89 5 times with a remainder of 14.
Record the quotient 5 as the next digit in the result. 
Result so far: 385.0
Deduct 75 from 89 and we're left with 14.
Include the next digit (7) from the dividend after 14, then repeat: 147 / 15

Step 5:
The number 15 fits into 147 9 times, leaving a remainder of 12.
Write down 9 as next digit of the result. 
Result so far: 3859.0
Deduct 135 from 147 and we're left with 12.
Take the next digit (5) from the dividend and append it to 12, then repeat: 125 / 15

Moving on to step 6:
When dividing 125 by 15, we get 8 with a remainder of 5.
Use 8 as the next digit of our solution. 
Result so far: 38598.0
Deduct 120 from 125 and we're left 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.

Going ahead to step 7:
15 can be fit into 50 3 times, resulting in a remainder of 5.
Write down 3 as next digit of the result. 
Result so far: 38598.3
If we take 45 away from 50, 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.

Moving on to step 8:
If we divide 50 by 15, we get 3 and a remainder of 5.
Use 3 as the next digit of our solution. 
Result so far: 38598.33
The remainder is 5 after subtracting 45 from 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

The final result is 38598.33 with a remainder of 0.005.