Kalkulu is Esperanto and means "work it out".

What is Esperanto

Esperanto is a constructed language for international communication. The language was invented more than 100 years ago in 1887 by the polak Ludwig Zamenhof. He was a genious in language who knew a lot about the fundamentals of language. Zamenhof wanted to make more understanding between people all over the world and he hoped that that would be easier if everybody knew the same language. It was never his intention to eliminate the national languages. Esperanto should be a supplement not a substitution.

Esperanto is strictly build by logic pieces. For example all verbs in the present ends with as. There are no exceptions and no irregular forms. The consequence in the building of the language makes it easy to learn. There are a lot of international words in the language, so it is often easy to guess the meaning of a short text. "La kato sidas sub la tablo" The cat sits under the table.

On lernu.net can you find more information about Esperanto.