Pronic Numbers Day - December 20
Happy Pronic Numbers Day! Pronic numbers (aka oblong numbers aka heteromecic numbers aka rectangular numbers) are the numbers obtained by multiplying consecutive non-negative integers together. The numbers start as: 0 X 1 = 0 1 X 2 = 2 2 X 3 = 6 3 X 4 = 12 4 X 5 = 20 It doesn't seem like pronic numbers are especially important, but they are old . It's believed that 6th century BC Pythagoreans knew about these numbers. The last 2 consecutive pronic numbers that form a date are 12/20, or December 20, which is why they're celebrated today.