Question: how many key used in Major C ?(Piano) Is that left hand B to right hand A?! Is That right ?!? 

Answer: Are you asking how many keys on a piano? there are 88. On the left side, the last note (lowest) is a A on the right side (highest), it is a C.\n\nIf you are asking how many pitches in the C major scale, the pitches are: C, D, E, F, G, A, B and C (octave above). On the entire piano, all the white keys are in C major.
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