I need help on this crossword ! Another word for Avogadro's Number?

It has 16 spaces on the crossword . The hint says "The number of things in one mole of a substance , specifically 6.02 x 10^23." I know that answer would be Avogadro's number , but it doesn't really work out because the 12th letter most likely has to be an "S" . so i'm wondering if there's another term for Avogadro's number ?