How many letters does the top answer for “a weight in the metric system; one tenth of a gram, equal to 1.5432 grains avoirdupois.” have?

The most common answer is decigram (8 letters).

Crossword clue: a weight in the metric system; one tenth of a gram, equal to 1.5432 grains avoirdupois.

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

decigram 8 letters web-def

1/10 gram

decigramme 10 letters web-def

A weight in the metric system; one tenth of a gram, equal to 1.5432 grains avoirdupois.