So basically I have to prove by induction that:
i) Given finite sets $A_{1},A_{2},...,A_{n}$ which are pairwise disjoint, then $|\cup_{i = 1}^{n}A_{i} | = \sum_{i = 1}^{n}|A_{i}|$.
ii) Given finite sets $A_{1},A_{2},...,A_{n}$, then $|\prod_{i = 1}^{n}A_{i} | = \prod_{i = 1}^{n}|A_{i}|$.
Appreciate any help given, Thanks
