What is the best way to identify correctly if a song is in C major scale or A minor scale, because notes are all the same?

Question

What is the best way to identify correctly if a song is in C major scale or A minor scale, because notes are all the same?

In: Other

Answer 1

Everyone else has answered it well, but I’d like to add that the notes are only the same if it’s A natural minor. There is also harmonic and melodic minor scale, which have a raised 7th note, or raised 6th and 7th.

So a piece in A minor could be identified by the use of F# and/or G#. Neither of these are likely to be in a piece in C major (though it’s not impossible).