15903049 ÷ 12 
The aim is to understand the frequency of 12 in 15903049.

Advancing to step 1:
When dividing 1 by 12, we get 0 with a remainder of 1.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 1, we end up with 1.
Append the next digit (5) from the dividend to 1 and continue with: 15 / 12

Step 2:
The number 12 fits into 15 1 times, leaving a remainder of 3.
The next digit of our result is 1. 
Result so far: 1.0
If we subtract 12 from 15, we get 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 12

Step 3:
39 divided by 12 is 3 with a remainder of 3.
Record the quotient 3 as the next digit in the result. 
Result so far: 13.0
If we subtract 36 from 39, we get 3.
Append the next digit (0) from the dividend to 3 and continue with: 30 / 12

Going ahead to step 4:
12 can be fit into 30 2 times, resulting in a remainder of 6.
The next digit of our result is 2. 
Result so far: 132.0
Subtracting 24 from 30 leaves us with 6.
Include the next digit (3) from the dividend after 6, then repeat: 63 / 12

Let's proceed to step 5:
When dividing 63 by 12, we get 5 with a remainder of 3.
Put 5 as the next digit of the answer. 
Result so far: 1325.0
The remainder is 3 after subtracting 60 from 63.
Take the next digit (0) from the dividend and append it to 3, then repeat: 30 / 12

Step 6:
12 goes into 30 2 times with a remainder of 6.
The next digit of our result is 2. 
Result so far: 13252.0
The remainder is 6 after subtracting 24 from 30.
Include the next digit (4) from the dividend after 6, then repeat: 64 / 12

Moving on to step 7:
12 can be fit into 64 5 times, resulting in a remainder of 4.
The next digit of our result is 5. 
Result so far: 132525.0
Subtract 60 from 64 to get 4.
Append the next digit (9) from the dividend to 4 and continue with: 49 / 12

Step 8:
49 divided by 12 is 4 with a remainder of 1.
Write down 4 as next digit of the result. 
Result so far: 1325254.0
Deduct 48 from 49 and we're left with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Let's proceed to step 9:
When dividing 10 by 12, we get 0 with a remainder of 10.
The next digit of our result is 0. 
Result so far: 1325254.0
If we subtract 0 from 10, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

On to step 10:
If we divide 100 by 12, we get 8 and a remainder of 4.
Write down 8 as next digit of the result. 
Result so far: 1325254.08
Subtract 96 from 100 to get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Going ahead to step 11:
When dividing 40 by 12, we get 3 with a remainder of 4.
The next digit of our result is 3. 
Result so far: 1325254.083
The remainder is 4 after subtracting 36 from 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

On to step 12:
12 goes into 40 3 times with a remainder of 4.
Use 3 as the next digit of our solution. 
Result so far: 1325254.0833
Subtracting 36 from 40 leaves us with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

The final result is 1325254.0833 with a remainder of 4e-05.