Counting above forty is in part based on a base 20 number system, called vigesimal: halvtred-s(inds-tyve) = 2½ x 20, tre-s(inds-tyve) = 3 x 20, halvfjerd-s(inds-tyve) = 3½ x 20, fir-s(inds-tyve) = 4 x 20, halvfem-s(inds-tyve) = 4½ x 20 (halvtredje, halvfjerde and halvfemte (lit.
The ones are placed before the tens with an intervening og ("and"): toogfyrre (42), seksoghalvfjers (76).