623809 ÷ 13 
The aim is to understand the frequency of 13 in 623809.

Let's proceed to step 1:
When dividing 6 by 13, we get 0 with a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Grab the next digit (2) from the dividend, add it to 6, then carry on: 62 / 13

Advancing to step 2:
If we divide 62 by 13, we get 4 and a remainder of 10.
The next digit of our result is 4. 
Result so far: 4.0
Subtract 52 from 62 to get 10.
Fetch the next digit (3) from the dividend, attach it to 10 and continue: 103 / 13

Going ahead to step 3:
If we divide 103 by 13, we get 7 and a remainder of 12.
Use 7 as the next digit of our solution. 
Result so far: 47.0
Subtract 91 from 103 to get 12.
Append the next digit (8) from the dividend to 12 and continue with: 128 / 13

Step 4:
13 goes into 128 9 times with a remainder of 11.
Use 9 as the next digit of our solution. 
Result so far: 479.0
Deduct 117 from 128 and we're left with 11.
Take the next digit (0) from the dividend and append it to 11, then repeat: 110 / 13

Going ahead to step 5:
If we divide 110 by 13, we get 8 and a remainder of 6.
The number 8 becomes the next digit in our result. 
Result so far: 4798.0
The remainder is 6 after subtracting 104 from 110.
Fetch the next digit (9) from the dividend, attach it to 6 and continue: 69 / 13

Step 6:
69 divided by 13 is 5 with a remainder of 4.
The next digit of our result is 5. 
Result so far: 47985.0
The remainder is 4 after subtracting 65 from 69.
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 7:
When dividing 40 by 13, we get 3 with a remainder of 1.
Put 3 as the next digit of the answer. 
Result so far: 47985.3
Subtract 39 from 40 to 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.

Moving on to step 8:
13 can be fit into 10 0 times, resulting in a remainder of 10.
The next digit of our result is 0. 
Result so far: 47985.3
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.

Going ahead to step 9:
100 divided by 13 is 7 with a remainder of 9.
Put 7 as the next digit of the answer. 
Result so far: 47985.307
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.

Moving on to step 10:
If we divide 90 by 13, we get 6 and a remainder of 12.
Put 6 as the next digit of the answer. 
Result so far: 47985.3076
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 11:
120 divided by 13 is 9 with a remainder of 3.
Write down 9 as next digit of the result. 
Result so far: 47985.30769
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.

Let's proceed to step 12:
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: 47985.307692
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.

Moving on to step 13:
13 goes into 40 3 times with a remainder of 1.
The number 3 becomes the next digit in our result. 
Result so far: 47985.3076923
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.

Advancing to step 14:
The number 13 fits into 10 0 times, leaving a remainder of 10.
The number 0 becomes the next digit in our result. 
Result so far: 47985.3076923
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.

The final result is 47985.3076923 with a remainder of 1e-08.