mathemachristian[he]

More importantly, what should be done with him to make him useful or at least neutral rather than being a negative on the society?

They are part of the society. Stop pitting the individual against the society and vice versa, if a society can’t support its members it needs to be abolished.

This will either sooth you because it’s so nice comparatively, or enrage you that it’s not the standard everywhere already but

The Ethiopian calendar has twelve months, all thirty days long, and five or six epagomenal days, which form a thirteenth month. A sixth epagomenal day is added every four years, without exception.