They're very nice problems; and I can see why the heading mentions Gauss, who is reputed, as a child, to have solved what looked like a complicated problem just by looking at it the right way. These are like that, each with an "elegant" solution that doesn't require extensive knowledge.
So, what help do you want? What ideas have you had? Have you tried just taking the time to ponder what each one involves, perhaps by experimenting or drawing a picture?