Instances where rule changes and/or irregularities occur without the intervention of a discernible base, e.g., in Russian (Slavic), ‘sorok’ 40 and ‘devjanosto’ 90 are irregular decades. In Welsh (and, in a parallel way, in Breton) (Celtic), a serialization rule 16= (1 on (5+10)), 17 = (2 on (5+10)), 19 = (4 on (5+10)) is interrupted by 18 = (2*9).
1. With base 10 many languages show a special rule for 11 and 12, before, with 13, serialization goes on along a more persistent rule. 2. Quite frequently, a base marks the change of a syntactic and/or semantic rule, as in the German examples 99 neunundneunzig, 100 hundert, 101 hundert(und)eins. Although such rules are frequent around bases in many languages, they are by no means necessary. Modern Greek shows a transition around base 100 without any intervening changes: 99 enenínda enéa (90+9), 100 ekatón, 101 ekatón éna (100+1).
1. With base 10 many languages show a special rule for 11 and 12, before, with 13, serialization goes on along a more persistent rule. 2. Quite frequently, a base marks the change of a syntactic and/or semantic rule, as in the German examples 99 neunundneunzig, 100 hundert, 101 hundert(und)eins. Although such rules are frequent around bases in many languages, they are by no means necessary. Modern Greek shows a transition around base 100 without any intervening changes: 99 enenínda enéa (90+9), 100 ekatón, 101 ekatón éna (100+1).