
The “test of the 9” is not infallible as it is believed: how it works and because it is said so
In Italian, when we use the way of saying “let’s do the proof of the nine”we mean that verify that will surely tell us if something is right or wrong. As if it were the latest confirmation we needed. This way of saying, however, was born from a False myth! In mathematics, The proof of the nine does not always ...







