The keyboard of a piano is made up of octaves with 5 black keys in each octave and one extra black key. There are 36 black keys on a piano. How many full octaves are there on a piano?

Hi there.
Let number of octaves be X.
Equation :
7x+1=36
7x=36-1
7x=35
X= 35/7
X= 5.
Therefore there are 5 number of black keys in an octave.
Hope it helps u.
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