Learn Icelandic: Fiskurinn er tuttugu og átta sentímetrar.

In Icelandic, compound numbers from 21 to 29, 31 to 39, and so on are made by combining the tens and the ones with the word og (and). This means 28 is literally formed as twenty and eight (tuttugu og átta).

Do tuttugu or átta change their endings to match the masculine word sentímetrar?

No, neither of them change here. While Icelandic numbers 1 through 4 must change to match the gender and case of the noun they are counting, numbers 5 and above (including átta and tuttugu) generally do not. They keep this exact form no matter what gender you are counting.

Why does sentímetrar end in -ar here?

The base word for centimeter is sentímetri, which is a masculine noun. Since the fish is 28 centimeters long, we need the plural form. For many masculine nouns that end in -i, the plural is formed by dropping the -i and adding -ar.

How does the word fiskurinn get its meaning of the fish?

The basic word for a fish is fiskur. In Icelandic, the word for the is usually not a separate word before the noun, but an ending attached directly to it. For a masculine noun like this, we add the definite article -inn to make it fiskurinn.