IPA: /ˌɪnɪɡˈzɛk(t)li/
KK: /ɪnɪɡˈzɛktli/
In a way that is not accurate or precise; done without exactness.
The measurements were taken inexactly, leading to errors in the final results.
Inexactly → It is formed from "in-" (meaning not) and "exact" (from Latin "exactus", meaning precise or accurate) and the suffix "-ly" (meaning in a manner of). The word "inexactly" means in a manner that is not precise or accurate.
Think of 'not' ('in-') being added to 'precise' ('exact') — that's why inexactly means not precise.