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.



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