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Q.
The number of all one-one functions from set $A=\{1,2,3\}$ to itself is
Relations and Functions - Part 2
Solution:
One-one function from $\{1,2,3\}$ to itself is simply a permutation on three symbols $1,2,3$. Therefore, total number of one-one maps from $\{1,2,3\}$ to itself is same as total number of permutations on symbols $1,2,3$, which is $3 !=6$