What is the rule for cualquier, cualquiera, and cualesquiera?

Question

I remember learning the rule for when to use **cualquier**, **cualquiera**, and **cualesquiera**, but was always confused about the exact differences. When should each be used, and what role do number, gender, and word placement play? Specifically, what should the translation be in the phrase "any of us," and why is that the proper choice?

Answer 1

Cualquier is used before singular noun forms in Spanish; Cual quieres? Which one do you want?; un profesor cualquiera is any teacher (profesor is male or female word); cualquier hombre is any man; cualquiera que sea is whatever it is; ser un cualquiera is to be a nobody; cuales means which ones or what (used in front of a plural noun); and cualesquiera is plural form of cualquiera as in cualesquieras personas. 'Any of us' might be construed as Cual o Cuales, denoting 'which of us or which ones of us.' The other Question Words/Interrogative Pronouns don't answer 'which one' or 'what', with the exception of Que, which answers what. I am stretching when I mention that quien? or quienes? answers who. I guess you could say, Who among us? Quienes entrenos o Quienes entre nosotros?