Learn Finnish: Kirja maksaa kaksikymmentäkaksi euroa.

In Finnish, any number greater than one requires the noun following it to be in the partitive case. Since the number is kaksikymmentäkaksi (twenty-two), the basic word euro takes the partitive ending -a to become euroa.

How do you break down the long number word, kaksikymmentäkaksi?

It translates literally to "two-tens-two". It is made up of kaksi (two), kymmentä (the partitive form of ten, meaning "tens"), and another kaksi (two). In Finnish, numbers like this are combined into one single compound word.

Does the verb maksaa mean "to cost" or "to pay"?

It actually means both! You can tell which one it is by the context. Here, since the subject is a book (kirja), it means "costs". If a person were the subject, like in Minä maksan (I pay), it would mean "pay".

Why isn't there a word for "The" before kirja?

Finnish does not have articles like "a", "an", or "the". The single word kirja can mean "a book" or "the book" depending entirely on the context of the conversation.