Answer: 51 notes span 6 octaves.
Explanation:
The word "octave" is a Latin word that means "eight".
In an instrument, Each octave is made up of 8 musical notes.
If we have 51 notes , the number of octaves can be made in it =

![=6.375\approx6\ \ \ \ \ \text{[Rounded to the nearest whole number]}](https://img.qammunity.org/2021/formulas/mathematics/high-school/aolj9s7bt8lo2rbyvknf6hfvgxftieivoi.png)
Hence, 51 notes span 6 octaves.