Let $E = \{1, 2, 3, 4\}$ and $F = \{1, 2\}$. Then, the number of onto functions from E to F is ______.

14

The total number of functions from E to F is $2^4=16$. Out of these 16 functions, we find that only two functions f and g given by $f(x)=1$ for all $x ∈E$ and, $g(x) = 2$ for all $x ∈E$ are into. Remaining 14 functions are onto.