Voyager key click

[i^4]

The divide key on my 11c clicks loudly when released after pressing it only slightly (less than 0.1mm). The key works normally except for the noise. Is the noise likely from a fractured snap disk or some other cause?
On another note, if a person writes a calculator program based on a unique published formula, can the program be published free w/o copyright problem?

[John Limpert]

In general, mathematical equations are not protected by copyright law.