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In this adaptation of "Everything I Ever Needed to Know About Economics I Learned from Online Dating, " Paul Oyer explains how our decisions to stick with people whose backgrounds resemble our own lead to stagnant economic mobility.

For math geeks, March 14 is a delicious holiday that celebrates one famous number -- pi or approximately 3.14. The mathematical constant, which is the ratio of a circle’s circumference to its diameter, can be used to find the area…