I recently reviewed how to count in Danish, and it uses a fairly unique system. In pretty much every language I've learned, multiples of ten are usually based on the other factor. That is, 2 times 10 is twenty, which is clearly based on the number "two." In Spanish, 4 x 10 is cuarenta, which is clearly based on the number "cuatro," and so on. Danish is unique in that numbers starting with fifty are based on multiples of 20, not 10.
20 tyve
50 halvtreds
60 tres
70 halvfjerds
80 firs
90 halvfems
Starting with 50, "halvtreds" is an abbreviation for "halv tred sinds tyve," where "halv tred" means 2.5 (though literally "half three", or one half less than three), "sinds" means "times" (as in to multiply), and "tyve" is twenty. So the number 50, instead of being based on 5 * 10 is actually based on 2.5 * 20.
Likewise, "tres" which is 60 is an abbreviation for "tre sinds tyve," which we've already established means 3 * 20.
The number four in Danish is "fire," and "halvfjerds" (70) is an abbreviation for "halv fire sinds tyve", or one half less than four (3.5) times 20, or simply 3.5 * 20 = 70. The number 80 is then simply "fire sinds tyve," or 4 * 20.
Finally, five is "fem." We should all see the pattern by now. One half less than five (halv fem) is four and a half. Multiply that times 20 and we get 90.
I was curious to see if this system of counting occurred in the other North Germanic, or Scandinavian languages. You can see what I found in Table 1.
So clearly, Swedish, Norwegian, and Icelandic all use the system where they multiple by ten. Faroese, the language spoken in the Faroe Islands which are a part of the Kingdom of Denmark, appears to use both systems. It also has the fewest speakers of all the North Germanic languages, making it hard to find a lot of written information on why it has two sets of numbers and when each are used.
If anyone is interested, I found this article on mentalfloss.com which discusses some other unique counting systems.
20 tyve
50 halvtreds
60 tres
70 halvfjerds
80 firs
90 halvfems
Starting with 50, "halvtreds" is an abbreviation for "halv tred sinds tyve," where "halv tred" means 2.5 (though literally "half three", or one half less than three), "sinds" means "times" (as in to multiply), and "tyve" is twenty. So the number 50, instead of being based on 5 * 10 is actually based on 2.5 * 20.
Likewise, "tres" which is 60 is an abbreviation for "tre sinds tyve," which we've already established means 3 * 20.
The number four in Danish is "fire," and "halvfjerds" (70) is an abbreviation for "halv fire sinds tyve", or one half less than four (3.5) times 20, or simply 3.5 * 20 = 70. The number 80 is then simply "fire sinds tyve," or 4 * 20.
Finally, five is "fem." We should all see the pattern by now. One half less than five (halv fem) is four and a half. Multiply that times 20 and we get 90.
I was curious to see if this system of counting occurred in the other North Germanic, or Scandinavian languages. You can see what I found in Table 1.
Table 1. Comparison of numbers in Scandinavian languages
So clearly, Swedish, Norwegian, and Icelandic all use the system where they multiple by ten. Faroese, the language spoken in the Faroe Islands which are a part of the Kingdom of Denmark, appears to use both systems. It also has the fewest speakers of all the North Germanic languages, making it hard to find a lot of written information on why it has two sets of numbers and when each are used.
If anyone is interested, I found this article on mentalfloss.com which discusses some other unique counting systems.
