Numbers from 0 to 5

With the exception of the number 0, which stems from Sanskrit, the etymology of the Khmer numbers from 1 to 5 is of proto-Austroasiatic origin.

• For details of the various alternative romanization systems, see Romanization of Khmer.
• Some authors may alternatively mark [ɓiː] as the pronunciation for the word two, and either [ɓəj] or [ɓei] for the word three.
• In neighbouring Thailand the number three is thought to bring good luck.^[8] However, in Cambodia, taking a picture with three people in it is considered bad luck, as it is believed that the person situated in the middle will die an early death.^[9][10]

Numbers from 6 to 20

The numbers from 6 to 9 may be constructed by adding any number between 1 and 4 to the base number 5 (ប្រាំ), so that 7 is literally constructed as 5 plus 2. Beyond that, Khmer uses a decimal base, so that 14 is constructed as 10 plus 4, rather than 2 times 5 plus 4; and 16 is constructed as 10+5+1.

Colloquially, compound numbers from eleven to nineteen may be formed using the word ដណ្ដប់ [dɔnɗɑp] preceded by any number from one to nine, so that 15 is constructed as ប្រាំដណ្ដប់ [pram dɔnɗɑp], instead of the standard ដប់ប្រាំ [ɗɑp pram].^[11]

• In constructions from 6 to 9 that use 5 as a base, [pram] may alternatively be pronounced [pəm]; giving [pəmmuəj], [pəmpiː], [pəmɓəj], and [pəmɓuːən]. This is especially true in dialects which elide [r], but not necessarily restricted to them, as the pattern also follows Khmer's minor syllable pattern.

Numbers from 30 to 90

The modern Khmer numbers from 30 to 90 are as follows:

• The word សិប [səp], which appears in each of these numbers, can be dropped in informal or colloquial speech. For example, the number 81 can be expressed as ប៉ែតមួយ [paet.muəj] instead of the full ប៉ែតសិបមួយ [paet.səp.muəj].

Historically speaking, Khmer borrowed the numbers from 30 to 90 from a southern Middle Chinese variety by way of a neighboring Tai language, most likely Thai.^[5] This is evidenced by the fact that the numbers in Khmer most closely resemble those of Thai, as well as the fact that the numbers cannot be deconstructed in Khmer. For instance, សែ [sae] is not used on its own to mean "four" in Khmer and សិប [səp] is not used on its own to mean "ten", while they are in Thai (see Thai numerals). The table below shows how the words in Khmer compare to other nearby Tai and Sinitic languages.

• Words in parentheses indicate literary pronunciations, while words preceded by an asterisk only occur in specific constructions and are not used for basic numbers from 3 to 10.

Prior to using a decimal system and adopting these words, Khmer used a base 20 system, so that numbers greater than 20 were formed by multiplying or adding on to the cardinal number for twenty. Under this system, 30 would've been constructed as (20 × 1) + 10 "twenty-one ten" and 80 was constructed as 4 × 20 "four twenties / four scores". See the section Angkorian numbers for details.

Numbers from 100 to 10,000,000

The standard Khmer numbers starting from one hundred are as follows:

Although មួយកោដិ [muəj kaot] is most commonly used to mean ten million, in some areas this is also colloquially used to refer to one billion (which is more properly មួយរយកោដិ [muəj rɔj kaot]). In order to avoid confusion, sometimes ដប់លាន [ɗɑp.liən] is used to mean ten million, along with មួយរយលាន [muəj.rɔj.liən] for one hundred million, and មួយពាន់លាន [muəj.pŏən.liən] ("one thousand million") to mean one billion.^[16]

Different Cambodian dialects may also employ different base number constructions to form greater numbers above one thousand. A few of the such can be observed in the following table:

Counting fruits

Reminiscent of the standard base 20 Angkorian Khmer numbers, the modern Khmer language also possesses separate words used to count fruits, not unlike how English uses words such as a "dozen" for counting items such as eggs.^[18]

Sanskrit and Pali influence

As a result of prolonged literary influence from both the Sanskrit and Pali languages, Khmer may occasionally use borrowed words for counting. Generally speaking, asides a few exceptions such as the numbers for 0 and 100 for which the Khmer language has no equivalent, they are more often restricted to literary, religious, and historical texts than they are used in day to day conversations. One reason for the decline of these numbers is that a Khmer nationalism movement, which emerged in the 1960s, attempted to remove all words of Sanskrit and Pali origin. The Khmer Rouge also attempted to cleanse the language by removing all words which were considered politically incorrect.^[19]

Ordinal numbers

Khmer ordinal numbers are formed by placing the word ទី [tiː] in front of a cardinal number.^[20][5] This is similar to the use of ที่ thi in Thai, and thứ (次) in Vietnamese.

Numbers from 5 to 10

Contrary to later forms of the Khmer numbers, Proto-Khmer possessed a single decimal number system. The numbers from one to five correspond to both the modern Khmer language and the proposed Mon–Khmer language, while the numbers from six to nine do not possess any modern remnants, with the number ten *kraaj (or *kraay) corresponding to the modern number for one hundred. It is likely that the initial *k, found in the numbers from six to ten, is a prefix.^[22]