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# If n(A) = 4, n(B) = 6, then the number of 1-1 functions from A to B is

$\begin{array}{1 1} 24 \\ 60 \\ 120 \\ 360 \end{array}$

Toolbox:
• If n(A)=m, n(B)=n then no. of functions from A to B=$n^m$
• No. of one-one functions = $^nP_m$
Ans: $^6P_4=\large\frac{6!}{2!}=360$
edited May 17, 2014