hexadecimal number system vs sexadecimal number system

hexadecimal number system and sexadecimal number system both are nouns.

Word	Noun	Adjective	Verb	Adverb
hexadecimal number system	Yes	No	No	No
sexadecimal number system	Yes	No	No	No

As nouns, hexadecimal number system and sexadecimal number system are synonyms defined as:

hexadecimal number system and sexadecimal number system: a positional system of numeration that uses hexadecimal digits and a radix of sixteen

Other synonyms of hexadecimal number system include hexadecimal system.

hexadecimal number system (noun)	sexadecimal number system (noun)
a positional system of numeration that uses hexadecimal digits and a radix of sixteen	a positional system of numeration that uses hexadecimal digits and a radix of sixteen