666819 divided by 15 
The aim is to understand the frequency of 15 in 666819.

Going ahead to step 1:
15 can be fit into 6 0 times, resulting in a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Take the next digit (6) from the dividend and append it to 6, then repeat: 66 / 15

Step 2:
The number 15 fits into 66 4 times, leaving a remainder of 6.
Put 4 as the next digit of the answer. 
Result so far: 4.0
Deduct 60 from 66 and we're left with 6.
Include the next digit (6) from the dividend after 6, then repeat: 66 / 15

On to step 3:
If we divide 66 by 15, we get 4 and a remainder of 6.
Use 4 as the next digit of our solution. 
Result so far: 44.0
If we subtract 60 from 66, we get 6.
Append the next digit (8) from the dividend to 6 and continue with: 68 / 15

Going ahead to step 4:
15 can be fit into 68 4 times, resulting in a remainder of 8.
Put 4 as the next digit of the answer. 
Result so far: 444.0
Deduct 60 from 68 and we're left with 8.
Append the next digit (1) from the dividend to 8 and continue with: 81 / 15

Step 5:
When dividing 81 by 15, we get 5 with a remainder of 6.
Put 5 as the next digit of the answer. 
Result so far: 4445.0
The remainder is 6 after subtracting 75 from 81.
Include the next digit (9) from the dividend after 6, then repeat: 69 / 15

Advancing to step 6:
15 can be fit into 69 4 times, resulting in a remainder of 9.
Write down 4 as next digit of the result. 
Result so far: 44454.0
The remainder is 9 after subtracting 60 from 69.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

On to step 7:
If we divide 90 by 15, we get 6 and a remainder of 0.
The number 6 becomes the next digit in our result. 
Result so far: 44454.6
If we take 90 away from 90, we end up with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Moving on to step 8:
When dividing 0 by 15, we get 0 with a remainder of 0.
The next digit of our result is 0. 
Result so far: 44454.6
Deduct 0 from 0 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Step 9:
0 divided by 15 is 0 with a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 44454.6
Subtract 0 from 0 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final outcome is 44454.6, with a leftover of 0.0.