Yes, Happy Mole Day (as in chemistry) !
In case you didn't take chemistry...or don't remember much from your chemistry class...a mole is the name for a number. Kind of like a dozen is the name for 12, or a million is the name for 1,000,000. One mole = 6.022x10^23 or 602,200,000,000,000,000,000,000. Moles are used in chemistry because atoms are so very small that you can fit a HUGE number of them in relatively small volumes. For instance a mole of water is 18 grams...or a little more than a tablespoon. Anyway...since the really important part of the number is the 10^23 part, October 23rd or 10/23 is National Mole Day. Today also marks the end of National Chemsitry Week.