Draw five number lines one under another so that their origins are on the same vertical line, and draw $\displaystyle C_1,\dots,C_5$ on them. Then try to guess which points belong to all $\displaystyle C_n$'s.
so as we go from 1 to infinity, the lim of 1 / n as n goes to infinity is 1/∞=0.
Using this, the union would be CN= [0, 3)
The intersection of CN = [1, 2)
I don't see the original problem anymore, so I am not sure. However, I think the right end of $\displaystyle C_n$ was $\displaystyle 2+1/n$, so 2 belongs to all $\displaystyle C_n$.