Learn Finnish: Nämä säästöt ovat nelinkertaisia!

When forming multiplicative adjectives with the suffix -kertainen, the numbers 2, 3, and 4 use a special combining form where the final vowel becomes an -i- before adding an -n. This gives us kaksinkertainen (double), kolminkertainen (triple), and nelinkertainen (quadruple). Most numbers from five onwards simply add -n to their base form, like viisinkertainen (fivefold) or kymmenenkertainen (tenfold).

Why is nelinkertaisia in the partitive plural instead of the nominative plural (nelinkertaiset)?

In Finnish, a predicative adjective (an adjective that describes the subject after the verb olla) must be in the partitive plural if the plural subject is abstract, uncountable, or expresses a mass. Because säästöt (savings) represents an abstract concept of money or resources rather than concrete, individual objects, the adjective takes the partitive plural nelinkertaisia.

Can the suffix -kertainen be used with words other than numbers?

Yes! While it is highly common with numbers, you can also attach it to certain adjectives and pronouns to express proportional amounts. A very common example for a B2 learner is moninkertainen, which translates to "manifold" or "many times over".

Does säästöt always have to be plural when talking about savings?