Bluebulb Projects' The Measure of Things presents:
120 is about one-and-two-fifths times the number of Keys on a Piano.
In other words, the count of Keys on a Piano is 0.71 times that amount.
(Moden layout; A0
Most modern keyboards have 88
keys, comprising seven octaves and an additional major third. A full-size, acoustic piano may have as many as 12,000