If I recall correctly we guessed this as children because the sound made by the rotary thing let go at "N" was the same as pressing the "hang" button N times I

If I recall correctly we guessed this as children because the sound made by the rotary thing let go at "N" was the same as pressing the "hang" button N times I mean it was an easy association to make, so at least a couple of friends guessed it. I can't remember if I was told or if I figured it out myself, but at least the explanation I was given involved this empirical observation