SOLUTION: A group of eight white piano keys makes one octave. To find the complete number of octaves subtract one then divide by seven. How many octaves are on a keyboard with fifty white ke

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Question 393494: A group of eight white piano keys makes one octave. To find the complete number of octaves subtract one then divide by seven. How many octaves are on a keyboard with fifty white keys
Answer by neatmath(302) About Me  (Show Source):
You can put this solution on YOUR website!

We are looking at a total of 50 keys.

They tell us to subtract 1 from that total, and divide by 7.

50-1=49

49%2F7=7

Thus, there should be 7 complete octaves on a piano with 50 keys.

It is easier to see this if you try to start from the beginning.

8 keys = 1 complete octave 8-1=7 7%2F7=1

15 keys = 2 complete octaves 15-1=14 14%2F7=2

22 keys = 3 complete octaves 22-1=21 21%2F7=3

And so on....

The reason this works the way it does is because the 8th key is not only the last key in the first octave, it is the first key in the second octave!

I hope this helps!