Abstract : The vast majority of the three hundred or so modern Tibeto-Burman languages have decimal numeral systems, like most contemporary languages, and more specifically like their large influential neighbours, the Sinitic and Indo-Aryan languages. Like most languages again, their favorite way of constructing higher numbers is by multiplication and addition.
On inquiry some of them reveal less common bases, 20, 12, 5 and even 4 as the building blocks of their number systems. These are used in parallel with a decimal system, mixed into it, or as the unique system of the language. Some are only traces and some are full-fledged systems, like Dzongkha, which can compute all numbers up to 160.000 (20⁴) including all intermediate numbers in its vigesimal system. Only the Maya language of Central America has been described with a comparable complexity.
Principles of number-building other than addition and multiplication, like fractions inside a number, or overcounting, which have become rare in other parts of the world, are also attested, although not always recognized by descriptors.
A complete typology of number systems has much to learn from Tibeto-Burman languages. More field-research is urgently needed to collect these fast disappearing systems, which foreign educators and local speakers alike unfortunately regard as a hindrance to socio-economic development.