Learn Finnish: Lopulta kaikki ymmärsivät ongelman. - In the end, everyone understood the problem.

In standard Finnish, when kaikki means "everyone" (referring to people), it acts as a plural pronoun and requires a plural verb, hence the -vät ending in ymmärsivät. This differs from English, where "everyone" takes a singular verb. Note that in casual spoken Finnish, you will very often hear the singular kaikki ymmärsi.

Why is "ongelman" in the genitive-accusative case instead of the partitive?

The object ongelman takes the -n ending because it is a total object: the action of understanding was completed, meaning they grasped the problem in its entirety. If you wanted to say they were beginning to understand or understood parts of it, you would use the partitive case: kaikki ymmärsivät ongelmaa.

How does the verb "ymmärtää" become "ymmärsivät" in the past tense?

When forming the past tense (imperfect) of ymmärtää, the final vowels drop to make room for the past tense marker -i. In Finnish, when a t meets this past tense i, it often changes to s (just like tietää becomes tiesi). This gives us the past stem ymmärsi-, to which we add the third-person plural ending -vät.

What is the literal meaning of "lopulta", and how does it differ from "viimein"?