Sorry, to me a "rack" of chips is 100 chips. The term "rack" can also be used to indicate a casino's inventory of its chip, so it can be a whole lot more. The rarity "R-X" system was something that has been included in the C&W price guides and is an "estimate" of the number of chips that the author's believe is availble or existence. An R-7 has an estimate of between 16-30 of one partiular chip, whereas an R-5 estimates aprox. 76-150 chips.