Inflecting compound numbers

The Auction Block

Welcome to the auction! Because inflecting large numbers in Finnish requires some mental gymnastics, this lesson keeps the vocabulary light so you can focus on the mechanics. Let's start with a couple of essential words.

The Golden Rule of Compound Numbers

Finnish numbers have a heavy but entirely consistent mechanic: when a compound number (like 21 or 25) takes a case ending, every single word within that number must take that same case ending.

If you want to say a bid is "at twenty-five euros" (using the inessive case, -ssa/-ssä), you must attach the ending to "two", "ten", "five", and "euros". To do this, you use their stems:

• kaksi (stem: kahde-) -> kahdessa
• kymmenen (stem: kymmene-) -> kymmenessä
• viisi (stem: viide-) -> viidessä

Written together as a single word, twenty-five becomes kahdessakymmenessäviidessä.

This rule applies perfectly to the elative case (-sta/-stä, meaning "from" or "out of"). If an auction starts from twenty-three euros, every part gets the -sta/-stä ending.

Applying to Other Cases

Once you master the stems, you can apply this to any case. If the auctioneer sells a painting for twenty-two euros, you use the adessive case (-lla/-llä) on every part.

When you raise a bid to a specific amount, you use the illative case (movement towards). The illative ending is a lengthened vowel + -n. Notice how it attaches to each constituent part to form kahteenkymmeneenneljään.

Finally, postpositions like jälkeen (after) require the preceding word to be in the genitive case (-n). Therefore, to say "after twenty-one bids", the number twenty-one becomes kahdenkymmenenyhden.