Enthuware

In such type of questions, you will need to work out the values of the loop variables for every iteration (unless you can recognize the pattern) on your worksheet.

How does one really recognize patterns like this, so that you don't have to go through the motions of keeping track of all the variables?

I always lose a lot of time on these kinds of questions.

It will improve with practice. Usually, it is done in the head, but in the beginning, you need to write down the value of each variable on a paper and updated it while following through the code.