It’s been years in the making, but former hedge-fund analyst Glen Whitney’s Museum of Mathematics (11 E. 26th St., nr. Fifth Ave.; 212-542-0566) finally bows December 15. At 19,000 square feet, it has 30-odd interactive exhibits that dig into what has traditionally been textbook territory, like fractals and tessellations. A 23-foot-tall paraboloid, which is like a multiplication table, illuminates the product of any two numbers one selects on a kiosk. Elsewhere, kids—and let’s be real, many adults—learn firsthand why a square-wheeled tricycle runs smoothly on a catenary curved track. Even MoMath’s automated ticket machine (admission starts at $15 for adults and $9 for children 12 and under) is perched on its side. “From the minute you walk in,” says associate director Cindy Lawrence, “we want to show you that math isn’t just straight lines and right angles.”