← The Keyboard Is a Number Line · Lesson 4 of 4
Eighty-eight keys
A full piano has 88 keys: seven full sets of twelve plus four extra. The lowest note is an A that vibrates 27.5 times a second; each octave up doubles it.
Smaller pianos and keyboards often have 61 or 76 keys, which still carry the same pattern of twos and threes.
A 61-key keyboard is how many full octaves of twelve, with how many left over?
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