We look at the division of 215042 by 13 
The aim is to understand the frequency of 13 in 215042.

Let's proceed to step 1:
13 can be fit into 2 0 times, resulting in a remainder of 2.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we subtract 0 from 2, we get 2.
Take the next digit (1) from the dividend and append it to 2, then repeat: 21 / 13

Advancing to step 2:
The number 13 fits into 21 1 times, leaving a remainder of 8.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Subtracting 13 from 21 leaves us with 8.
Grab the next digit (5) from the dividend, add it to 8, then carry on: 85 / 13

On to step 3:
If we divide 85 by 13, we get 6 and a remainder of 7.
Use 6 as the next digit of our solution. 
Result so far: 16.0
Deduct 78 from 85 and we're left with 7.
Bring next digit (0) of the dividend behind the 7 and repeat the process: 70 / 13

Let's proceed to step 4:
When dividing 70 by 13, we get 5 with a remainder of 5.
Write down 5 as next digit of the result. 
Result so far: 165.0
If we take 65 away from 70, we end up with 5.
Include the next digit (4) from the dividend after 5, then repeat: 54 / 13

Let's proceed to step 5:
13 can be fit into 54 4 times, resulting in a remainder of 2.
Use 4 as the next digit of our solution. 
Result so far: 1654.0
If we subtract 52 from 54, we get 2.
Include the next digit (2) from the dividend after 2, then repeat: 22 / 13

Advancing to step 6:
If we divide 22 by 13, we get 1 and a remainder of 9.
The next digit of our result is 1. 
Result so far: 16541.0
Deduct 13 from 22 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.

Let's proceed to step 7:
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: 16541.6
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.

Step 8:
120 divided by 13 is 9 with a remainder of 3.
The number 9 becomes the next digit in our result. 
Result so far: 16541.69
Subtracting 117 from 120 leaves us 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.

Moving on to step 9:
When dividing 30 by 13, we get 2 with a remainder of 4.
Use 2 as the next digit of our solution. 
Result so far: 16541.692
If we subtract 26 from 30, we 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.

Step 10:
13 goes into 40 3 times with a remainder of 1.
Use 3 as the next digit of our solution. 
Result so far: 16541.6923
Subtracting 39 from 40 leaves us 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.

On to step 11:
13 can be fit into 10 0 times, resulting in a remainder of 10.
Put 0 as the next digit of the answer. 
Result so far: 16541.6923
If we take 0 away from 10, we end up 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.

Moving on to step 12:
When dividing 100 by 13, we get 7 with a remainder of 9.
Put 7 as the next digit of the answer. 
Result so far: 16541.692307
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 13:
90 divided by 13 is 6 with a remainder of 12.
The next digit of our result is 6. 
Result so far: 16541.6923076
Deduct 78 from 90 and we're left 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.

Step 14:
13 can be fit into 120 9 times, resulting in a remainder of 3.
The number 9 becomes the next digit in our result. 
Result so far: 16541.69230769
Subtracting 117 from 120 leaves us 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.

After the division, we end up with 16541.69230769 and a remainder of 3e-09.