quantitative vs quantity

quantitative is not a noun while quantity is a noun.

Word	Noun	Adjective	Verb	Adverb
quantitative	No	Yes	No	No
quantity	Yes	No	No	No

quantitative (noun)	quantity (noun)
	how much there is or how many there are of something that you can quantify
	an adequate or large amount
	the concept that something has a magnitude and can be represented in mathematical expressions by a constant or a variable

quantitative (adjective)	quantity (adjective)
expressible as a quantity or relating to or susceptible of measurement
(of verse) having a metric system based on relative duration of syllables
relating to the measurement of quantity