- Double partitive of moni, "partitive" of monta; (not) many (kinds of)
- Pöydällä oli monta juustoa.
- Many cheeses were on the table. (many pieces, but not necessarily different kinds)
- Pöydällä oli montaa juustoa.
- Many kinds of cheeses were on the table.
Considered nonstandard until 1995. Used where monta effectively acts as a nominative when used as a determiner or numeral, meaning "many".
- Näin monta lintua.
- I saw many birds.
- En nähnyt montaa lintua.
- I didn't see many birds.
With verbs that require a partitive, montaa is used instead of monta.
- Rakastan montaa ihmistä.
- I love many people / I'm in love with many (more than one) people.
- A help page by the Institute for the Languages of Finland describing the uses of "monta" and "montaa" (in Finnish)