Questions & Answers about Kolme ja kolme on kuusi.
Why do we use on (is) instead of the plural form for "are"?
In basic Finnish math sentences, the verb olla (to be) is always in the third-person singular form on (is). Even though you are adding multiple numbers together, you do not use the plural form ovat.
Are the numbers kolme and kuusi in their basic dictionary form here?
Yes! When stating simple math facts like this, the numbers stay in their basic nominative form. Later you will learn that Finnish numbers can change their endings depending on their role in a sentence, but for basic equations, they stay exactly as you learn them in the dictionary.
Doesn't the word kuusi also mean "fir tree"?
You are right! Kuusi is a famous Finnish word because it has multiple meanings. It can mean "six" or "fir tree" (and a few other things). You just have to use the context to tell them apart. Since this sentence is adding kolme ja kolme (three and three), it is clear that kuusi means the number six here.
Could I say "plus" instead of ja for an addition sentence?
Absolutely. It is very common to use the word plus in spoken Finnish, which would make the sentence kolme plus kolme on kuusi. Using ja (and) is also perfectly correct and common, especially when you are first learning the numbers.