Learn Icelandic: Mannfjöldinn er samtals tuttugu þúsund. - The population is in total twenty thousand.

Even though it translates as a number, þúsund is technically a neuter noun in Icelandic. When counting multiples like twenty thousand, we just put the base number tuttugu in front of it. Because the plural form of þúsund is identical to the singular form, it stays exactly the same here!

What are the parts that make up the word mannfjöldinn?

It is a compound noun made of two words plus a definite article (the). Mann- is a root form of maður (person), and fjöldi means number or multitude. Finally, the -nn at the end is the masculine definite article making it THE population.

Why does samtals end in an -s? Is it a plural?

No, the -s is not a plural marker here. It is actually a leftover possessive (genitive) ending. The root is samtal (a total), and adding the -s turns it into a handy adverb meaning 'in total' or 'altogether'. You will hear this word very often when receiving a bill or calculating a sum!

Does tuttugu change its ending depending on what is being counted?

No. In Icelandic, only the numbers 1 through 4 change their forms to match the gender of the noun they describe. Because 20 is well above 4, tuttugu stays exactly the same, no matter what you are counting.