@isuruf I implemented a Singleton class in #846 . Could you please look into it. I am at a fix here. I have changed the inheritances too. Though I have not implemented add, sub etc, I plan to implement them soon.
@nishnik, you should have mentioned solutions to inequalities. I was thinking along the lines of what arb does. If you are using it for returning solutions to inequalities, then you don't need to inherit from Number. Just from Basic is enough.