Hi, I hear that in Czech there are 2 ways to express number? eg. 28, in Czech we can say "dvacet osm" or "osmadvacet", right? If so, what is the grammatical rule of the expression for the latter, like "osmadvacet"? Many thanks

It is true. it's for 21 – 99. Jedenadvacet or jednadvacet dvaadvacet třiadvacet čtyřiadvacet pětadvacet šestadvacet sedmadvacet (spelling: se-dm-a-dva-cet or sed-ma-dva-cet) osmadvacet (spelling: o-sm-a-dva-cet or os-ma-dva-cet) devětadvacet The same way for -třicet, -čtyřicet, ... , -devadesát. As you know, this form is one-word. That form "dvacet osm" separates the words. Germans use this one-word form. (acht-und-zwanzig). What about ordinals: 28. (28st)? dvacátý osmý (dvacátá osmá etc.) osmadvacátý (osmadvacátá atc.) What about declesion? with 28 men s dvaceti osmi muži s osmadvaceti muži

There is no special grammatical rule. The addition of numbers is commutative, since x + y = y + x. For example 20 + 8 = 8 + 20, since both expressions equal 28. We read: dvacet a osm se rovná (= is equal to) osm a dvacet Both expressions (in the decimal system) express the abstract quantity 28. Rule 1. If we read a number in descending order the conjunction "a" is omitted in most cases: 3928 = 3000+900+20+8: tři tisíce [a] devět set [a] dvacet [a] osm but usually 1001 = 1000+1 (nights): tisíc a jedna (noc) (tisíc jeden/jedna/jedno is also possible) Rule 2. If we read a number in ascending order the conjunction is not omitted, however it is applicable only for the range 21-99: 28 = 8+20: osm a dvacet 99 = 9+90: devět a devadesát Rule 3. The expressions like osm a dvacet are considered as one word. Thus only the last numeral is declinable: s osmadvaceti studenty (with 28 students), but s dvaceti osmi studenty;