How many letters does the top answer for “of or pertaining to a number system having 16 as its base” have?

The most common answer is hex (3 letters).

Crossword clue: of or pertaining to a number system having 16 as its base

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

hex 3 letters wn-def

an evil spell

hexadecimal 11 letters wn-def

of or pertaining to a number system having 16 as its base