Way back in 2011, a developer asked to be able to get a colour number value from RGBA codes.
Someone somewhere had done the calculations which I put together on a
google sheet. @ 45 developers have since accessed the sheet.
Maybe you didn't know that you can use a number instead of the colour blocks to set the colour of a component in AI2?
The above will produce Black.
Finally got around to creating an app to do the same thing!
It is in the Gallery as Android Colour Number Finder
Hopefully has a use in some situations ;)