complex number vs complex quantity

complex number and complex quantity both are nouns.

Word	Noun	Adjective	Verb	Adverb
complex number	Yes	No	No	No
complex quantity	Yes	No	No	No

As nouns, complex number and complex quantity are synonyms defined as:

complex number and complex quantity: (mathematics) a number of the form a+bi where a and b are real numbers and i is the square root of -1

Other synonyms of complex number include imaginary, imaginary number.

complex number (noun)	complex quantity (noun)
(mathematics) a number of the form a+bi where a and b are real numbers and i is the square root of -1	(mathematics) a number of the form a+bi where a and b are real numbers and i is the square root of -1