Write the total number of one-one functions from set A = {1, 2, 3, 4} to set B = {a, b, c}.

A has 4 elements and $B$ has 3 elements.

Also, one-one function is only possible from $A$ to $B$ if $n(A) \leq n(B)$.

But, here $n(A)>n(B)$.

So, the number of one-one functions from $A$ to $B$ is 0 .