Hello all,
I have always had problems with loop tracking problems, I seem to understand how the loop runs and when it ends and the general idea of how it works. However, when I take a programming test and I need to track the output of a short loop, I fail most of the time. Can someone please help me? or give me some strategy tips?

The problem below is an example, I need to find the output of SUM without a computer, just using logic and a pencil and paper.

This is what I got for my i, and sum;

i
0
3
9
12

sum:
0
3
6
9
12

So in my attempt: sum= 12 but the correct answer is sum=30.

Code:
```int main () {

int sum=0, i=0;

while (i <=12) {
sum = sum +i;  // before this read sum=sum+1 which was a typo:/
i= i+3;
}
printf("%d", sum);```

2. sum increase by 1 each time through the loop. i increases by 3 each time. Your sum values posted above are thus wrong and you are missing a 6 in your list of i values.

3. Darn!

Sorry, there was a typo in the segment of code
I edited it, the correct answer for sum=30.

Can someone please help me understand whats going on? Can you basically solve this and think out loud so I can follow your thought pattern and learn from it?

4. Originally Posted by hk_mp5kpdw
sum increase by 1 each time through the loop.
No, it does not.

5. Originally Posted by grumpy
No, it does not.
It did... in the original version of his post. (He edited it)

6. Not so difficult to follow on paper (values below taken at end of each loop):
Code:
```i    sum
3    0
6    3  (0  +  3)
9    9  (3  +  6)
12   18 (9  +  9)
15   30 (18 + 12)```

7. Originally Posted by hk_mp5kpdw
Not so difficult to follow on paper (values below taken at end of each loop):
Code:
```i    sum
3    0
6    3  (0  +  3)
9    9  (3  +  6)
12   18 (9  +  9)
15   30 (18 + 12)```

Thank you very much! That clarifies. I finally get it!

Thanks again man, take care.

8. Also, two NOOB questions

a) What is the format to randomize a number? for example a number between 15-100.

would it be rand(15)%100?

b)How come the answer to this is 15?

13+20/(5+3%4)

I get 4.125 for my answer:

1)3%4=3
2)5+3=8
3)13+20=33
4)33/8=4.125