We look at the division of 280188 by 13 
The aim is to understand the frequency of 13 in 280188.

On to step 1:
13 goes into 2 0 times with a remainder of 2.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 2 after subtracting 0 from 2.
Take the next digit (8) from the dividend and append it to 2, then repeat: 28 / 13

On to step 2:
If we divide 28 by 13, we get 2 and a remainder of 2.
Put 2 as the next digit of the answer. 
Result so far: 2.0
If we subtract 26 from 28, we get 2.
Bring next digit (0) of the dividend behind the 2 and repeat the process: 20 / 13

Let's proceed to step 3:
If we divide 20 by 13, we get 1 and a remainder of 7.
Use 1 as the next digit of our solution. 
Result so far: 21.0
If we subtract 13 from 20, we get 7.
Grab the next digit (1) from the dividend, add it to 7, then carry on: 71 / 13

Let's proceed to step 4:
If we divide 71 by 13, we get 5 and a remainder of 6.
The next digit of our result is 5. 
Result so far: 215.0
The remainder is 6 after subtracting 65 from 71.
Fetch the next digit (8) from the dividend, attach it to 6 and continue: 68 / 13

On to step 5:
13 goes into 68 5 times with a remainder of 3.
Use 5 as the next digit of our solution. 
Result so far: 2155.0
If we subtract 65 from 68, we get 3.
Fetch the next digit (8) from the dividend, attach it to 3 and continue: 38 / 13

Let's proceed to step 6:
When dividing 38 by 13, we get 2 with a remainder of 12.
Use 2 as the next digit of our solution. 
Result so far: 21552.0
Subtracting 26 from 38 leaves us 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 7:
13 goes into 120 9 times with a remainder of 3.
Put 9 as the next digit of the answer. 
Result so far: 21552.9
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.

Step 8:
13 goes into 30 2 times with a remainder of 4.
Use 2 as the next digit of our solution. 
Result so far: 21552.92
Deduct 26 from 30 and we're left 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 9:
The number 13 fits into 40 3 times, leaving a remainder of 1.
Put 3 as the next digit of the answer. 
Result so far: 21552.923
If we subtract 39 from 40, we get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Step 10:
10 divided by 13 is 0 with a remainder of 10.
The number 0 becomes the next digit in our result. 
Result so far: 21552.923
The remainder is 10 after subtracting 0 from 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Let's proceed to step 11:
The number 13 fits into 100 7 times, leaving a remainder of 9.
Put 7 as the next digit of the answer. 
Result so far: 21552.92307
If we subtract 91 from 100, we get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Step 12:
The number 13 fits into 90 6 times, leaving a remainder of 12.
The number 6 becomes the next digit in our result. 
Result so far: 21552.923076
Subtracting 78 from 90 leaves us 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.

Moving on to step 13:
The number 13 fits into 120 9 times, leaving a remainder of 3.
Put 9 as the next digit of the answer. 
Result so far: 21552.9230769
If we take 117 away from 120, we end up 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.

Advancing to step 14:
13 can be fit into 30 2 times, resulting in a remainder of 4.
The number 2 becomes the next digit in our result. 
Result so far: 21552.92307692
Subtracting 26 from 30 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 21552.92307692 with a remainder of 4e-09.