664821 ÷ 15 
The aim is to understand the frequency of 15 in 664821.

Let's proceed 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
If we subtract 0 from 6, we get 6.
Include the next digit (6) from the dividend after 6, then repeat: 66 / 15

Step 2:
When dividing 66 by 15, we get 4 with a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 4.0
Subtract 60 from 66 to get 6.
Bring next digit (4) of the dividend behind the 6 and repeat the process: 64 / 15

Step 3:
15 can be fit into 64 4 times, resulting in a remainder of 4.
Write down 4 as next digit of the result. 
Result so far: 44.0
If we take 60 away from 64, we end up with 4.
Append the next digit (8) from the dividend to 4 and continue with: 48 / 15

Advancing to step 4:
15 can be fit into 48 3 times, resulting in a remainder of 3.
The next digit of our result is 3. 
Result so far: 443.0
Subtracting 45 from 48 leaves us with 3.
Fetch the next digit (2) from the dividend, attach it to 3 and continue: 32 / 15

Going ahead to step 5:
When dividing 32 by 15, we get 2 with a remainder of 2.
Record the quotient 2 as the next digit in the result. 
Result so far: 4432.0
Deduct 30 from 32 and we're left with 2.
Include the next digit (1) from the dividend after 2, then repeat: 21 / 15

On to step 6:
15 goes into 21 1 times with a remainder of 6.
Record the quotient 1 as the next digit in the result. 
Result so far: 44321.0
The remainder is 6 after subtracting 15 from 21.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Moving on to step 7:
When dividing 60 by 15, we get 4 with a remainder of 0.
Use 4 as the next digit of our solution. 
Result so far: 44321.4
If we take 60 away from 60, 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.

Let's proceed to step 8:
15 can be fit into 0 0 times, resulting in a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 44321.4
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:
The number 15 fits into 0 0 times, leaving a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 44321.4
The remainder is 0 after subtracting 0 from 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 quotient of the division is 44321.4, and the remainder is 0.0.