  The principle of correspondence (or classical limit) is essential in quantum
mechanics. Yet, how and why quantum phenomena vanish at the macroscopic scale
are issues still open to debate. Here, quantum mechanical predictions for
Greenberger-Horne-Zeilinger states of qubits are shown to be easier to
reproduce with a classical model as the number of particles increases, even in
the absence of loopholes or conspiratorial mechanisms of any kind. It is
conjectured that this result may lead to the simplest way to express the
principle of correspondence.
