A Year of Mathematics 2015 Calendar

Brand new for 2015: the first "A Year of Mathematics" wall calendar. JANUARY: Prime, Deficient, Perfect, Abundant, and Amicable numbers. Mersenne primes. Why September is named after the number seven. FEBRUARY: What we can say about integers that we cannot say about rational numbers, the Waring problem, the war on Groundhog Day. MARCH: Irrational numbers (algebraic and transcendental) and the history of Daylight Savings Time. APRIL: To Infinity and Beyond. When Worlds Collide: Earth Day = Administrative Professionals' Day. MAY: You're not just imagining things about the square root of -1; arithmetic gets complex. JUNE: Pascal's Triangle, combinatorics, and figurative numbers. JULY: Polar and non-orthogonal coordinates AUGUST: Bizarro binary a.k.a. base -2. SEPTEMBER: Tricks with 9. OCTOBER: We rarely know the particular day "that thing" was discovered in mathematics. Except October 16. NOVEMBER: Averages that are anything but average. DECEMBER: This calendar marks birthdays of famous mathematicians. What are the odds two share a day? Learn about numbers and number systems, planes and parallel lines, twelve ways to say "2015," and wish "Happy Birthday" to 46 great mathematicians.