351186 ÷ 15 
The aim is to understand the frequency of 15 in 351186.

Step 1:
The number 15 fits into 3 0 times, leaving a remainder of 3.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we subtract 0 from 3, we get 3.
Append the next digit (5) from the dividend to 3 and continue with: 35 / 15

Moving on to step 2:
35 divided by 15 is 2 with a remainder of 5.
Record the quotient 2 as the next digit in the result. 
Result so far: 2.0
The remainder is 5 after subtracting 30 from 35.
Bring next digit (1) of the dividend behind the 5 and repeat the process: 51 / 15

Going ahead to step 3:
51 divided by 15 is 3 with a remainder of 6.
Use 3 as the next digit of our solution. 
Result so far: 23.0
Deduct 45 from 51 and we're left with 6.
Fetch the next digit (1) from the dividend, attach it to 6 and continue: 61 / 15

Let's proceed to step 4:
When dividing 61 by 15, we get 4 with a remainder of 1.
Put 4 as the next digit of the answer. 
Result so far: 234.0
The remainder is 1 after subtracting 60 from 61.
Fetch the next digit (8) from the dividend, attach it to 1 and continue: 18 / 15

Step 5:
When dividing 18 by 15, we get 1 with a remainder of 3.
The next digit of our result is 1. 
Result so far: 2341.0
Subtract 15 from 18 to get 3.
Bring next digit (6) of the dividend behind the 3 and repeat the process: 36 / 15

Let's proceed to step 6:
The number 15 fits into 36 2 times, leaving a remainder of 6.
Record the quotient 2 as the next digit in the result. 
Result so far: 23412.0
The remainder is 6 after subtracting 30 from 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

On to step 7:
60 divided by 15 is 4 with a remainder of 0.
Write down 4 as next digit of the result. 
Result so far: 23412.4
Subtracting 60 from 60 leaves us 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:
15 goes into 0 0 times with a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 23412.4
If we subtract 0 from 0, we 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.

Moving on to step 9:
0 divided by 15 is 0 with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 23412.4
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.

Our division results in 23412.4 with a remaining 0.0.