The total number of injective mappings from a set with m elements to a set with n elements for m > n, is
m!n!(m−n)!
m!(m−n)!
nm
zero
If A and B are two finite sets, and f:A→B is an injective mapping, then n(A)≤n(B)
As m > n, there does not exist any mapping from set with n elements.