Which Is It 1 Years Old Or 1 Year Old Duplicate

Possible Duplicate: Prove 0! = 1 0! = 1 from first principles Why does 0! = 1 0! = 1? All I know of factorial is that x! x! is equal to the product of all the numbers that come before it. Furthermore, Possible Duplicate: How do I convince someone that $1+1=2$ may not necessarily be true? I once read that some mathematicians provided a very length proof of $1+1=2$. Moreover, The series does not converge, because as you observe, the partial sums $1,0,1,0,\ldots$ oscillate and do not approach a single limit. In related context, I'm self-learning Linear Algebra and have been trying to take a geometric approach to understand what matrices mean visually. These findings regarding Which Is It 1 Years Old Or 1 Year Old Duplicate provide comprehensive context for understanding this subject.