For convenience' sake we give the numerals themselves before mentioning the suffixes.
The Romanic numerals are used with a few modifications to make them easier to handle: 1 un (or uni, which is more emphatic), 2 du, 3 tri, 4 quar, 5 sink, 6 six, 7 sep, 8 ok, 9 nin: this is suggested by E nine, Sc ni, nio, D neun, as the Romanic forms nov, non would cause conflict with the words for 'new' and 'not'. 10 dek (dis is 'this'), 100 sent, 1000 mil . . . milione, miliarde (mil miliones), bilione (milione miliones) [not an American billion (DB)].
Un may be used as an indefinite article, but such an article is generally superfluous.
It would be possible to express other numerals simply by combinations like dekdu 12, dudek 20, dudekdu 22, etc. But it is a common experience that people are apt to mistake dekdu for dudek and inversely, and most languages have forms which cannot be so easily mistaken; therefore it is practical for the tens to use the Romanic ending -ANTI (-i because adjectival): 20 duanti, 30 trianti, 40 quaranti, 50 sinkanti, 60 sixanti, 70 sepanti, 80 okanti, 90 ninanti; 23 duanti tri, 99 ninanti nin, etc.
Substantives may be formed in -o; duo, trio, etc., dekduo a dozen, duanto a score. No ambiguity arises from the fact that -o is used here in a different sense from that in Substantival Suffixes.
The Esp eystem is particularly bewildering for Germans, whose dreizehn means 13, while tridek means 30. Note also the difficulty in dictating long sets of numbers, where 3, 10, 20, 7 may easily be misheard as 30, 27, or 30, 2, 17.
The Ido system of composite numerals (70 sepadek, 17 dekesep) is rather confusing. There is an ingenious system of counting by means of syllables invented by G. de Kolovrat (Les cent syllabes, Nice, 1927): ba 0, be 1, bi 2, bo 3, bu 4--ca 5, ce 6, ci 7, co 8, cu 9--da 10, de 11 . . . fa 15 . . . gi 22 . . . ho 28 . . . ka 35, etc., zu 99; caburi 50462, femina 16750. It would in many ways be advantageous, could these numerals be introduced internationally, but provisionally we must have some system like the above.
The use of cardinal numbers in cases like the year 1927, page 37, chapter X, etc., is not logical, but very convenient; it is found in most of our languages; the French extend it to names of kings, etc., Louis quatorze, and to the days of the month, le quatorze juin. In Russian the more logical ordinals are used even in the indication of years.
Ordinal numbers end in -ESMI: unesmi first, duesmi, sentesmi, etc. 345th trisent-quaranti-sinkesmi. From these we have adverbs in -im: unesmim firstly, in the first place, etc.
Fractions: 100th part sentime (cp. the French coin), half duime, five sixths sink siximes, etc. Prefix mi- = half.
Duopli double, duoplim doubly; in the same way triopli, sentopli, etc.
Distributive adverbs are formed by means of -opim: triopim in threes, three at a time. The same ending is used in pokopim little by little.