Let $f :$ {1,2,3,4,5} $\rightarrow$ {1,2,3,4,5,6} Be a Function

Short Answer

Let $f :$ {1,2,3,4,5} $\rightarrow$ {1,2,3,4,5,6} be a function.
(a) How many total functions are there?
(b) How many of these functions are one-to-one?