puzzle

Suppose you are given (1) a natural number N; (2) a set of natural num-
bers S = {n1; n2; : : : }; (3) a set of arithmetic operators, say +; -;*; =
(with the usual meaning of addition, multiplication, substraction, di-
vision). Your job is to construct an arithmetic expression R built from
the given operators and using each of the numbers in S exactly once,
with R = N.
(a) Explain in general how you could solve that problem.
(b) Solve the speci c instance: N = 24, S = {1; 3; 4; 6}