Breakdown of Точность этого измерения — ноль целых одна тысячная грамма.
этот
this [f: эта, n: это]
один
one
грамм
gram
ноль
zero
Questions & Answers about Точность этого измерения — ноль целых одна тысячная грамма.
Why does ноль take the genitive plural целых here?
The word целая (whole) acts as a noun in decimal fractions. Because it is quantified by ноль (zero), it takes the genitive plural form, just as any countable noun would after zero, five, or more.
Why is одна тысячная in the feminine form when the noun it measures, грамм, is masculine?
Fractions in Russian implicitly agree with the feminine noun часть (part). You are literally saying "one thousandth [part]", so both the numeral одна and the ordinal тысячная must be feminine.
Why is грамма in the genitive singular?
The noun being measured by a fraction always takes the genitive case, translating to "of a gram". It is genitive singular because it refers to a single gram being divided into parts.
In English we often say "zero point zero zero one". Can I drop целых in Russian and just say ноль одна тысячная?
No, in Russian you must explicitly state the "whole" parts when reading decimals. You cannot skip целых, even when the value is zero.