The ten roots
satu 1, dua 2, tiga 3, empat 4, lima 5, enam 6, tujuh 7, delapan 8, sembilan 9,
sepuluh 10.
Everything else is built from these.
Teens use belas
Add belas to the root.
sebelas 11, dua belas 12, tiga belas 13, empat belas 14
Note sebelas, not satu belas. The prefix se- means one, and it replaces satu in compounds throughout the language.
Tens use puluh
dua puluh 20, tiga puluh 30, empat puluh 40
Literally ‘two tens’, ‘three tens’.
The trap
dua belas is 12
dua puluh is 20
Two words that sound similar, in a country where you will hear them at speed while someone tells you a price. This is worth over-practising, because the difference between twelve thousand and twenty thousand rupiah is exactly the kind of thing you notice later.
Combining
Read them left to right, exactly as they are built.
dua puluh satu 21
lima puluh tujuh 57
seratus 100
dua ratus lima puluh 250
Big numbers, because of the currency
Indonesian money runs in thousands, so ribu is unavoidable from day one.
seribu 1,000
sepuluh ribu 10,000
seratus ribu 100,000
sejuta 1,000,000
What you’ll actually hear
Prices get shortened aggressively. Dua puluh ribu ‘twenty thousand’ becomes dua puluh, and often just dua puluh ribu said fast enough that only the dua is clear.
At a market, goceng is five thousand and ceban is ten thousand. These come from Hokkien, they are not in any textbook, and you will hear them constantly in Java.