Bijection: R -> R*

ITT bijections from the reals to the non-zero reals. I'm stumped.

>>1
Let {a_n} be a sequence of non-zero real numbers. Define the function f(x) as follows: if x = 0, f(x) = a_1. If x = a_i, f(x) = a_(i+1). Otherwise, f(x) = x.