We look at the division of 687400 by 13 
The aim is to understand the frequency of 13 in 687400.

Step 1:
If we divide 6 by 13, we get 0 and a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Bring next digit (8) of the dividend behind the 6 and repeat the process: 68 / 13

Advancing to step 2:
13 can be fit into 68 5 times, resulting in a remainder of 3.
Record the quotient 5 as the next digit in the result. 
Result so far: 5.0
If we take 65 away from 68, we end up with 3.
Include the next digit (7) from the dividend after 3, then repeat: 37 / 13

Step 3:
When dividing 37 by 13, we get 2 with a remainder of 11.
Record the quotient 2 as the next digit in the result. 
Result so far: 52.0
Subtract 26 from 37 to get 11.
Fetch the next digit (4) from the dividend, attach it to 11 and continue: 114 / 13

Step 4:
If we divide 114 by 13, we get 8 and a remainder of 10.
Write down 8 as next digit of the result. 
Result so far: 528.0
Deduct 104 from 114 and we're left with 10.
Grab the next digit (0) from the dividend, add it to 10, then carry on: 100 / 13

Step 5:
13 goes into 100 7 times with a remainder of 9.
Record the quotient 7 as the next digit in the result. 
Result so far: 5287.0
If we take 91 away from 100, we end up with 9.
Bring next digit (0) of the dividend behind the 9 and repeat the process: 90 / 13

Moving on to step 6:
When dividing 90 by 13, we get 6 with a remainder of 12.
Write down 6 as next digit of the result. 
Result so far: 52876.0
Subtract 78 from 90 to 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.

Let's proceed to step 7:
13 goes into 120 9 times with a remainder of 3.
Use 9 as the next digit of our solution. 
Result so far: 52876.9
If we subtract 117 from 120, we get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Let's proceed to step 8:
13 can be fit into 30 2 times, resulting in a remainder of 4.
The next digit of our result is 2. 
Result so far: 52876.92
Subtract 26 from 30 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.

Advancing to step 9:
13 goes into 40 3 times with a remainder of 1.
Write down 3 as next digit of the result. 
Result so far: 52876.923
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 10:
If we divide 10 by 13, we get 0 and a remainder of 10.
Write down 0 as next digit of the result. 
Result so far: 52876.923
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.

On to step 11:
The number 13 fits into 100 7 times, leaving a remainder of 9.
Record the quotient 7 as the next digit in the result. 
Result so far: 52876.92307
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.

Let's proceed to step 12:
90 divided by 13 is 6 with a remainder of 12.
Put 6 as the next digit of the answer. 
Result so far: 52876.923076
The remainder is 12 after subtracting 78 from 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Going ahead to step 13:
13 can be fit into 120 9 times, resulting in a remainder of 3.
Record the quotient 9 as the next digit in the result. 
Result so far: 52876.9230769
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.

On to step 14:
13 can be fit into 30 2 times, resulting in a remainder of 4.
Use 2 as the next digit of our solution. 
Result so far: 52876.92307692
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 outcome is 52876.92307692, with a leftover of 4e-09.