<p>A function f from set A into set B is a rule which assigns each element x in A, a unique (one and only one) element (denoted by f(x) in B. A function of set from A into B is called an onto function, if for each element y in B there is some element x in A, such that f(x)=y. Now suppose that A= {1,2,⋯,n} and B={1,2,3}. Determine the total number of onto functions of A into B.</p>