15879054 divided by 13 
The aim is to understand the frequency of 13 in 15879054.

Step 1:
13 goes into 1 0 times with a remainder of 1.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 1 after subtracting 0 from 1.
Include the next digit (5) from the dividend after 1, then repeat: 15 / 13

Let's proceed to step 2:
The number 13 fits into 15 1 times, leaving a remainder of 2.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
The remainder is 2 after subtracting 13 from 15.
Fetch the next digit (8) from the dividend, attach it to 2 and continue: 28 / 13

Advancing to step 3:
13 goes into 28 2 times with a remainder of 2.
Write down 2 as next digit of the result. 
Result so far: 12.0
The remainder is 2 after subtracting 26 from 28.
Take the next digit (7) from the dividend and append it to 2, then repeat: 27 / 13

Going ahead to step 4:
When dividing 27 by 13, we get 2 with a remainder of 1.
Write down 2 as next digit of the result. 
Result so far: 122.0
Deduct 26 from 27 and we're left with 1.
Append the next digit (9) from the dividend to 1 and continue with: 19 / 13

Step 5:
13 can be fit into 19 1 times, resulting in a remainder of 6.
Write down 1 as next digit of the result. 
Result so far: 1221.0
If we subtract 13 from 19, we get 6.
Take the next digit (0) from the dividend and append it to 6, then repeat: 60 / 13

Moving on to step 6:
When dividing 60 by 13, we get 4 with a remainder of 8.
The next digit of our result is 4. 
Result so far: 12214.0
Subtracting 52 from 60 leaves us with 8.
Bring next digit (5) of the dividend behind the 8 and repeat the process: 85 / 13

Advancing to step 7:
13 goes into 85 6 times with a remainder of 7.
Use 6 as the next digit of our solution. 
Result so far: 122146.0
The remainder is 7 after subtracting 78 from 85.
Take the next digit (4) from the dividend and append it to 7, then repeat: 74 / 13

Let's proceed to step 8:
If we divide 74 by 13, we get 5 and a remainder of 9.
Record the quotient 5 as the next digit in the result. 
Result so far: 1221465.0
Deduct 65 from 74 and we're left with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Advancing to step 9:
If we divide 90 by 13, we get 6 and a remainder of 12.
Use 6 as the next digit of our solution. 
Result so far: 1221465.6
If we take 78 away from 90, we end up with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Let's proceed to step 10:
When dividing 120 by 13, we get 9 with a remainder of 3.
Put 9 as the next digit of the answer. 
Result so far: 1221465.69
Deduct 117 from 120 and we're left with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

On to step 11:
When dividing 30 by 13, we get 2 with a remainder of 4.
Write down 2 as next digit of the result. 
Result so far: 1221465.692
If we take 26 away from 30, we end up 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.

Step 12:
13 can be fit into 40 3 times, resulting in a remainder of 1.
Record the quotient 3 as the next digit in the result. 
Result so far: 1221465.6923
If we take 39 away from 40, we end up 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.

Advancing to step 13:
If we divide 10 by 13, we get 0 and a remainder of 10.
The next digit of our result is 0. 
Result so far: 1221465.6923
Subtracting 0 from 10 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Advancing to step 14:
When dividing 100 by 13, we get 7 with a remainder of 9.
Use 7 as the next digit of our solution. 
Result so far: 1221465.692307
Deduct 91 from 100 and we're left with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Going ahead to step 15:
When dividing 90 by 13, we get 6 with a remainder of 12.
Put 6 as the next digit of the answer. 
Result so far: 1221465.6923076
If we subtract 78 from 90, we get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Moving on to step 16:
The number 13 fits into 120 9 times, leaving a remainder of 3.
The next digit of our result is 9. 
Result so far: 1221465.69230769
The remainder is 3 after subtracting 117 from 120.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

The final outcome is 1221465.69230769, with a leftover of 3e-09.