Let's divide 399116 by 15
The aim is to understand the frequency of 15 in 399116.

Step 1:
15 can be fit into 3 0 times, resulting in a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 3 after subtracting 0 from 3.
Take the next digit (9) from the dividend and append it to 3, then repeat: 39 / 15

Going ahead to step 2:
15 goes into 39 2 times with a remainder of 9.
Write down 2 as next digit of the result. 
Result so far: 2.0
The remainder is 9 after subtracting 30 from 39.
Bring next digit (9) of the dividend behind the 9 and repeat the process: 99 / 15

Going ahead to step 3:
15 goes into 99 6 times with a remainder of 9.
The number 6 becomes the next digit in our result. 
Result so far: 26.0
Subtracting 90 from 99 leaves us with 9.
Grab the next digit (1) from the dividend, add it to 9, then carry on: 91 / 15

Advancing to step 4:
When dividing 91 by 15, we get 6 with a remainder of 1.
Write down 6 as next digit of the result. 
Result so far: 266.0
The remainder is 1 after subtracting 90 from 91.
Fetch the next digit (1) from the dividend, attach it to 1 and continue: 11 / 15

Let's proceed to step 5:
When dividing 11 by 15, we get 0 with a remainder of 11.
Put 0 as the next digit of the answer. 
Result so far: 2660.0
If we subtract 0 from 11, we get 11.
Bring next digit (6) of the dividend behind the 11 and repeat the process: 116 / 15

Advancing to step 6:
15 can be fit into 116 7 times, resulting in a remainder of 11.
The next digit of our result is 7. 
Result so far: 26607.0
Subtract 105 from 116 to get 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Moving on to step 7:
15 goes into 110 7 times with a remainder of 5.
Use 7 as the next digit of our solution. 
Result so far: 26607.7
Deduct 105 from 110 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.

Advancing to step 8:
15 can be fit into 50 3 times, resulting in a remainder of 5.
Put 3 as the next digit of the answer. 
Result so far: 26607.73
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.

Step 9:
When dividing 50 by 15, we get 3 with a remainder of 5.
The next digit of our result is 3. 
Result so far: 26607.733
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.

After the division, we end up with 26607.733 and a remainder of 0.0005.