Usually uncountable; plural exactnesses is possible but rare.
Translations
The exactness of the measurements made the experiment reliable.
L'exactitude des mesures a rendu l'expérience fiable.
précisionSurtout pour les détails, les mesures ou l'expression. Definitions
the quality of being exact; accuracy or precision in details, measurement, or expression The exactness of the measurements made the experiment reliable.
strict conformity to facts, rules, a standard, or an original model She checked the translation for exactness against the original text.