129511 divided by 13 
The aim is to understand the frequency of 13 in 129511.

Step 1:
If we divide 1 by 13, we get 0 and a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 1 after subtracting 0 from 1.
Fetch the next digit (2) from the dividend, attach it to 1 and continue: 12 / 13

Moving on to step 2:
If we divide 12 by 13, we get 0 and a remainder of 12.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 12, we end up with 12.
Include the next digit (9) from the dividend after 12, then repeat: 129 / 13

Moving on to step 3:
When dividing 129 by 13, we get 9 with a remainder of 12.
Write down 9 as next digit of the result. 
Result so far: 9.0
If we subtract 117 from 129, we get 12.
Fetch the next digit (5) from the dividend, attach it to 12 and continue: 125 / 13

On to step 4:
13 can be fit into 125 9 times, resulting in a remainder of 8.
Write down 9 as next digit of the result. 
Result so far: 99.0
The remainder is 8 after subtracting 117 from 125.
Grab the next digit (1) from the dividend, add it to 8, then carry on: 81 / 13

Going ahead to step 5:
13 can be fit into 81 6 times, resulting in a remainder of 3.
The number 6 becomes the next digit in our result. 
Result so far: 996.0
If we take 78 away from 81, we end up with 3.
Include the next digit (1) from the dividend after 3, then repeat: 31 / 13

Step 6:
The number 13 fits into 31 2 times, leaving a remainder of 5.
The next digit of our result is 2. 
Result so far: 9962.0
The remainder is 5 after subtracting 26 from 31.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

On to step 7:
The number 13 fits into 50 3 times, leaving a remainder of 11.
Put 3 as the next digit of the answer. 
Result so far: 9962.3
If we take 39 away from 50, we end up with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Going ahead to step 8:
The number 13 fits into 110 8 times, leaving a remainder of 6.
Put 8 as the next digit of the answer. 
Result so far: 9962.38
Subtracting 104 from 110 leaves us with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Step 9:
If we divide 60 by 13, we get 4 and a remainder of 8.
The next digit of our result is 4. 
Result so far: 9962.384
If we subtract 52 from 60, we get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Step 10:
13 can be fit into 80 6 times, resulting in a remainder of 2.
Use 6 as the next digit of our solution. 
Result so far: 9962.3846
If we subtract 78 from 80, we get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Going ahead to step 11:
When dividing 20 by 13, we get 1 with a remainder of 7.
Use 1 as the next digit of our solution. 
Result so far: 9962.38461
If we take 13 away from 20, we end up with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Let's proceed to step 12:
13 goes into 70 5 times with a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 9962.384615
Deduct 65 from 70 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.

On to step 13:
The number 13 fits into 50 3 times, leaving a remainder of 11.
Use 3 as the next digit of our solution. 
Result so far: 9962.3846153
If we subtract 39 from 50, we 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.

Going ahead to step 14:
13 can be fit into 110 8 times, resulting in a remainder of 6.
Use 8 as the next digit of our solution. 
Result so far: 9962.38461538
The remainder is 6 after subtracting 104 from 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

The final outcome is 9962.38461538, with a leftover of 6e-09.