Question: Prove Theorem by mathematical induction.
Theorem: The Multiplication Rule
If an operation consists of k steps and the first step can be performed in n1 ways, the second step can be performed in n2 ways [regardless of how the first step was performed], the kth step can be performed in nk ways [regardless of how the preceding steps were performed], then the entire operation can be performed in n1n2 ··· nk ways.