Nearest completed quarter

Question

Is there a C# function which will give me the last day of the most recently finished Quarter given a date?

For example,

var lastDayOfLastQuarter = So         


        

Answer 1

Func q = (i) => { return ((i - 1) / 3) + 1; };

Test:

Enumerable.Range(1, 12).Select(i => q(i));