603916 divided by 13 
The aim is to understand the frequency of 13 in 603916.

Let's proceed to step 1:
The number 13 fits into 6 0 times, leaving a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Include the next digit (0) from the dividend after 6, then repeat: 60 / 13

Advancing to step 2:
13 can be fit into 60 4 times, resulting in a remainder of 8.
Put 4 as the next digit of the answer. 
Result so far: 4.0
The remainder is 8 after subtracting 52 from 60.
Bring next digit (3) of the dividend behind the 8 and repeat the process: 83 / 13

On to step 3:
If we divide 83 by 13, we get 6 and a remainder of 5.
Record the quotient 6 as the next digit in the result. 
Result so far: 46.0
Subtract 78 from 83 to get 5.
Append the next digit (9) from the dividend to 5 and continue with: 59 / 13

Moving on to step 4:
13 can be fit into 59 4 times, resulting in a remainder of 7.
Write down 4 as next digit of the result. 
Result so far: 464.0
If we subtract 52 from 59, we get 7.
Bring next digit (1) of the dividend behind the 7 and repeat the process: 71 / 13

Step 5:
71 divided by 13 is 5 with a remainder of 6.
Write down 5 as next digit of the result. 
Result so far: 4645.0
If we subtract 65 from 71, we get 6.
Include the next digit (6) from the dividend after 6, then repeat: 66 / 13

Moving on to step 6:
If we divide 66 by 13, we get 5 and a remainder of 1.
Put 5 as the next digit of the answer. 
Result so far: 46455.0
If we subtract 65 from 66, 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 7:
10 divided by 13 is 0 with a remainder of 10.
The next digit of our result is 0. 
Result so far: 46455.0
Deduct 0 from 10 and we're left 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.

Advancing to step 8:
When dividing 100 by 13, we get 7 with a remainder of 9.
The number 7 becomes the next digit in our result. 
Result so far: 46455.07
Subtract 91 from 100 to 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.

Going ahead to step 9:
13 goes into 90 6 times with a remainder of 12.
Use 6 as the next digit of our solution. 
Result so far: 46455.076
If we subtract 78 from 90, we 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.

Moving on to step 10:
120 divided by 13 is 9 with a remainder of 3.
The number 9 becomes the next digit in our result. 
Result so far: 46455.0769
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.

On to step 11:
If we divide 30 by 13, we get 2 and a remainder of 4.
The number 2 becomes the next digit in our result. 
Result so far: 46455.07692
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.

On to step 12:
13 can be fit into 40 3 times, resulting in a remainder of 1.
The next digit of our result is 3. 
Result so far: 46455.076923
The remainder is 1 after subtracting 39 from 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Step 13:
10 divided by 13 is 0 with a remainder of 10.
Record the quotient 0 as the next digit in the result. 
Result so far: 46455.076923
If we subtract 0 from 10, we get 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 14:
When dividing 100 by 13, we get 7 with a remainder of 9.
Record the quotient 7 as the next digit in the result. 
Result so far: 46455.07692307
The remainder is 9 after subtracting 91 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Our division results in 46455.07692307 with a remaining 9e-09.