878039 divided by 15 
The aim is to understand the frequency of 15 in 878039.

Step 1:
If we divide 8 by 15, we get 0 and a remainder of 8.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 8 leaves us with 8.
Fetch the next digit (7) from the dividend, attach it to 8 and continue: 87 / 15

Moving on to step 2:
87 divided by 15 is 5 with a remainder of 12.
The next digit of our result is 5. 
Result so far: 5.0
Subtract 75 from 87 to get 12.
Append the next digit (8) from the dividend to 12 and continue with: 128 / 15

Let's proceed to step 3:
128 divided by 15 is 8 with a remainder of 8.
The next digit of our result is 8. 
Result so far: 58.0
Deduct 120 from 128 and we're left with 8.
Take the next digit (0) from the dividend and append it to 8, then repeat: 80 / 15

Going ahead to step 4:
15 can be fit into 80 5 times, resulting in a remainder of 5.
The next digit of our result is 5. 
Result so far: 585.0
If we take 75 away from 80, we end up with 5.
Bring next digit (3) of the dividend behind the 5 and repeat the process: 53 / 15

Moving on to step 5:
If we divide 53 by 15, we get 3 and a remainder of 8.
Use 3 as the next digit of our solution. 
Result so far: 5853.0
If we subtract 45 from 53, we get 8.
Bring next digit (9) of the dividend behind the 8 and repeat the process: 89 / 15

Step 6:
15 can be fit into 89 5 times, resulting in a remainder of 14.
The next digit of our result is 5. 
Result so far: 58535.0
The remainder is 14 after subtracting 75 from 89.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Going ahead to step 7:
15 can be fit into 140 9 times, resulting in a remainder of 5.
Use 9 as the next digit of our solution. 
Result so far: 58535.9
Subtract 135 from 140 to 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 8:
15 can be fit into 50 3 times, resulting in a remainder of 5.
Record the quotient 3 as the next digit in the result. 
Result so far: 58535.93
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.

Advancing to step 9:
When dividing 50 by 15, we get 3 with a remainder of 5.
Write down 3 as next digit of the result. 
Result so far: 58535.933
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.

The quotient of the division is 58535.933, and the remainder is 0.0005.