Returning the Favor 541993 = 159211275242599 and 15921 + 12752 + 42599 = 71272 712723 = 362040234715648 and 36204 + 02347 + 15648 = 54199 (From Edward Barbeau’s Power Play, 1997.) March 18, 2020March 18, 2020 | Science & Math