La duono de ses estas tri, the half of six is three.
Li estis nur duone atenta, he was only half attentive.
La triona parto de ses estas du, the third part of six is two.
Dek unu dekduonoj, eleven twelfths.
Mi dudekone finis la laboron, I one-twentieth finished the work.
DESCRIPTIVE COMPOUNDS.
167. A compound word whose first element modifies the second in an adjectival or adverbial relation is called a descriptive compound. The final -a or -e of the first element may be omitted, unless the resulting combination would be ambiguous or harsh-sounding.
a. When the first element is adverbial (an adverb or preposition), the second element may be either an adverb or adjective:
multekosta, expensive.
duonkolere, half angrily.
nevidebla, invisible.
nevole, involuntarily.
ruĝflava (ruĝeflava), reddish yellow.
survoje, on the way, en route.
antaŭhieraŭ, day before yesterday.
postmorgaŭ, day after tomorrow.
b. An adjective may be used for the first element, if the second is an adverb or adjective derived from a noun-root:
samtempa, contemporaneous.
unufoje, once, one time.
trifoje, thrice, three times.
unutaga, one day's, of one day.
unuataga, the first day's.
frutempe, at an early time.
c. A noun may be used for the second element, if the resulting word has not merely unity of form, but also unity of meaning with a slightly different sense from that expressed by the noun and adjective uncombined:
In national languages a change of accent often accompanies such change in meaning, as bla'ckberry (not black be'rry), blu'ebird (not blue bi'rd), swee'theart (not sweet hea'rt), German ju'ngfrau, virgin (not jung frau', young woman), etc.
bonveno, a welcome (not "bona veno", a good coming).
libertempo, a vacation, leisure (not "libera tempo", free time).
superjaro, leap-year (not "super jaro", above a year).
bondeziroj, good wishes, felicitations (not "bonaj deziroj", good desires).
plimulto, a majority (adverb and noun combined).