The basic plural adds -t: talo becomes talot. But that -t only survives as a subject; as soon as a case ending follows, the plural is marked by an -i- inside the word instead - taloissa means "in the houses".
Examples
- Talot ovat vanhoja.
- The houses are old.
- Asun taloissa lähellä.
- I live in the houses nearby.
- Minulla on kaksi veljeä.
- I have two brothers.
The mistake to avoid
After a number the noun is SINGULAR partitive, not plural: kaksi veljeä, not "kaksi veljet".
Where this fits in
Food & ordering, Finnish A1: Order at a café or restaurant, ask for the bill, and talk about basic food and drink.