Esperanto: A Complete and Comprehensive Grammar/Numbers

Numbers

In Esperanto, the cardinal numbers are all built up from little more than a dozen words:

0 Nul
1 Unu
2 Du
3 Tri
4 Kvar
5 Kvin
6 Ses
7 Sep
8 Ok
9 Naŭ
10 Dek
11 Dek Unu
12 Dek Du
20 Dudek
30 Tridek
100 Cent
1,000 Mil
1,000,000 Miliono
1,000,000,000 Miliardo
1,000,000,000,000 Biliono

All other numbers are simply built up from these. To give a couple of examples:

16 Dek ses (one ten and six)
42 Kvardek du (four tens and two)
442 Kvarcent kvardek du (four hundreds, four tens and two)
1,729 Mil sepcent dudek naŭ (one thousand, seven hundreds, two tens and nine)
22,729 Dudek du mil sepcent dudek naŭ (Twenty two thousands, seven hundreds, two tens and nine)
3,022,729 Tri milionoj dudek du mil sepcent dudek naŭ (three millions, twenty two thousands, seven hundreds, two tens and nine)
4,003,022,729 Kvar miliardoj tri milionoj dudek du mil sepcent dudek naŭ (four billions, three millions, twenty two thousands, seven hundreds, two tens and nine)
5,004,003,022,729 Kvin bilionoj kvar miliardoj tri milionoj dudek du mil sepcent dudek naŭ (five trillions, four billions, three millions, twenty two thousands, seven hundreds, two tens and nine)

The ordinal numbers (first, second, third, etc.) are simply adjectives and are formed as all other adjectives in Esperanto, as will be detailed in the chapter on adjectives.