Hi,

What you need to do is to look at the table that you created in part 1 and look for all the occasions where the remaining number is 1, noting the value of n that you started with.

You should see some kind of relationship with all of the n's that you find. For example, are they all even, all odd, all squared numbers?

Using this rule that matches all of the n's you should be able to determine the remaining number for 300 in the final part of the question.