Continuing the previous subject, let's talk more about the usage of numbers with the verb in singular and plural. If we take the follwoing example:
"Kaksi poikaa juoksee kadulla" and "Kaksi poikaa juoksevat kadulla".
The verb is used in the singular in the first example meaning that "
Kaksi poikaa" refers to some unidentified, unspecified group of (two) boys
part of a bigger group of (possibly whole set of) boys. The plural form usage in the second example implies that there are only two of the boys in that particular context (which is missing in our example). To take another example, the sentence "
Perheen kaksi poikkaa ovat ulkomailla" implies that there are only two boys in the family, and
all of them are abroad.
The same way: "
Neljä pohjoismaata osallistui kongressiin" implies that there exist more than four nordic countries, while saying "Viisi pohjoismaata osallistuivat kongressiin" also tells us that there are exactly five nordic countries and
all of them took part in the congress.
Thanks to H-M for these clarifycations.