Numerical prefixes can be used to construct words that refer to a specific quantity of something. For example, in chemistry, carbon dioxide refers to a molecule containing two (di) oxygen atoms. A tetrahedron is a polyhedron with four (tetra) identical faces. A pentagram is a five-pointed star figure. Chemistry (from the Greek word χημεία (chemeia) meaning cast together or pour together) is the science of matter at the atomic to molecular scale, dealing primarily with collections of atoms (such as molecules, crystals, and metals). ... A tetrahedron (plural: tetrahedra) is a polyhedron composed of four triangular faces, three of which meet at each vertex. ... A polyhedron is a geometric shape which in mathematics is defined by three related meanings. ... A pentagram, pentalpha, or pentangle A pentagram (sometimes known as pentalpha or pentangle) is a five-pointed star drawn with five straight strokes. ...

The following numerical prefixes are from the Greek language: In linguistics, a prefix is a type of affix that precedes the morphemes to which it can attach. ... Greek (, IPA — Hellenic) has a documented history of 3,500 years, the longest of any single language within the Indo-European family. ...

• 1. mono
• 2. di
• 3. tri
• 4. tetra
• 5. penta
• 6. hexa
• 7. hepta
• 8. octa
• 9. ennea
• 10. deca
• 11. hendeca
• 12. dodeca
• 13. triskaideka
• 20. icosa
• 21. icosakaihena
• 30. triconta
• 40. tetraconta
• 50. pentaconta
• 60. hexaconta
• 70. heptaconta
• 80. octaconta
• 90. enneaconta
• 100. hecta
• 1000. chilia (ch pronounced /k/ in English)
• 10,000. myria

In practice, people often use the Latin prefixes nona and "undeca" for 9 and 11 instead of the Greek ennea and "hendeca". Prefixes above 12 are not commonly used, except 20 in icosahedron, 100 in hectare, and 1000 in the metric system. Mono- is a Greek (language) prefix, meaning one (a single object or property) Monopoly, the control of a market by a single entity. ... This page is a candidate to be moved to Wiktionary. ... Tri- or tria- is a numerial prefix meaning 3 that can be either Greek or Latin; though occasionally tre- and ter- also exist for Latin. ... Tetra is a Greek prefix meaning 4 (in constrast to quad- as in quadruped, which is Latin). ... Penta- is a Greek prefix meaning five. ... Hexa- is a Greek prefix meaning six. ... Hepta- is a Greek prefix for 7. ... Octa- is a Greek (language) prefix meaning eight. ... Ennea- is the Greek numerical prefix for 9. ... Deca- is a Greek prefix meaning ten (see Greek numerical prefixes. ... Dodeca- is a Greek (language) prefix meaning twelve. ... Triskaideka- is a Greek prefix meaning thirteen. ... Icosa- is a Greek (language) prefix meaning twenty. ... Hecta- is a Greek (language) prefix meaning one hundred. ... Chilia- (pronounced KIL-ee-uh) is the Greek numerical prefix for 1000. ... Myria is an obsolete prefix in the SI system of units that denoted a factor of 10+4 (ten thousand, 10,000). ... An icosahedron [ˌaıkəsəhiːdrən] noun (plural: -drons, -dra [-drə]) is a polyhedron having 20 faces, but usually a regular icosahedron is meant, which has faces which are equilateral triangles. ... A hectare (symbol ha) is a unit of area, equal to 10,000 square meters, commonly used for measuring land area. ... The International System of Units (symbol: SI) (for the French phrase Syst me International dUnit s) is the most widely used system of units. ...

See also

• Latin numerical prefixes