Major scales are the most important piano scales: firstly, because they are very common and, secondly, because they are fundamental to understand keys. If you hear someone mention that a piano piece is played in A Major, it means that it depends on the A Scale. Intervals: 1, 2, 3, 4, 5, 6, 7 Semi-notes: 2-2-1 -2-2-2-1 The Piano Scales Collection