@elasticsoul this is correct. In Danish the names for 50, 60, 70, 80, and 90 comes from multiples of 20. And given that
2.5 times 20 is 50, that is pronounced half-three-times-twenty, where half-three means 2.5 (half-way to three). In Danish: Halvtredsindstyve
3 times 20 is 60, so three-times-twenty is 60. In Danish: Tredsindstyve.
And so on and so forth.