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Number	Multiplier		Number	Multiplier
1	mono-		32	dotriaconta-
2	di-		40	tetraconta-
3	tri-		50	pentaconta-
4	tetra-		60	hexaconta-
5	penta-		70	heptaconta-
6	hexa-		80	octaconta-
7	hepta-		90	nonaconta-
8	octa-		100	hecta-
9	nona-		200	dicta-
10	deca-		300	tricta-
11	undeca-		400	tetracta-
12	dodeca-		500	pentacta-
13	trideca-		600	hexacta-
14	tetradeca-		700	heptacta-
15	pentadeca-		800	octacata-
16	hexadeca-		900	nonacta-
17	heptadeca-		1000	kilia-
18	octadeca-		2000	dilia-
19	nonadeca-		3000	trilia-
20	icosa-[1]		4000	tetralia-
21	henicosa-		5000	pentalia-
22	docosa-		6000	hexalia-
23	tricosa-		7000	heptalia-
30	triconta-		8000	octalia-
31	hentriconta-		9000	nonalia-

The numerical multiplier (or multiplying affix) in IUPAC nomenclature indicates how many particular atoms or functional groups are attached at a particular point in a molecule. The affixes are derived from both Latin and Greek.

Contents 1 Compound affixes 1.1 The numeral one 1.2 The numeral two 2 Icosa- v. eicosa- 3 Etymology 4 Source

The affix for a number larger than twelve is constructed is the opposite order to that which the number is written in Hindu-Arabic numerals: units, then tens, then hundreds, then thousands. For example:

548 → octa- (8) + tetraconta- (40) + pentacta- (500) = octatetracontapentacta-

9267 → hepta- (7) + hexaconta- (60) + dicta- (200) + nonalia- (9000) = heptahexacontadictanonalia-

While the use of the affix mono- is rarely necessary in organic chemistry, it is often essential in inorganic chemistry to avoid ambiguity: carbon oxide could refer to either carbon monoxide or carbon dioxide. In forming compound affixes, the numeral one is represented by the term hen- except when it forms part of the number eleven (undeca-): hence

241 → hen- (1) + tetraconta- (40) + dicta- (200) = hentetracontadicta-

411 → undeca- (11) + tetracta- (400) = undecatetracta-

In compound affixes, the numeral two is represented by do- except when it forms part of the numbers 20 (icosa-), 200 (dicta-) or 2000 (dilia-).

IUPAC prefers the spelling icosa- for the affix corresponding to the number twenty on the grounds of etymology. However both the Chemical Abstracts Service and the Beilstein database use the alternative spelling eicosa-.

"mono-" is from Greek monos = "alone". "un" = 1 and "nona-" = 9 are from Latin. The others are derived from Greek numbers.

Linguists should note that the forms 100 and upwards are not correct Greek. In Ancient Greek, hekaton = 100, diakosioi = 200, triakosioi = 300, etc, khīlioi = 1000, diskhīlioi = 2000, triskhīlioi = 3000, etc, and 13 to 19 are treiskaideka etc with the Greek for "and" inserted (as in triskaidekaphobia).

Panico, R.; & Powell, W. H. (Eds.) (1994). A Guide to IUPAC Nomenclature of Organic Compounds 1993. Oxford: Blackwell Science. ISBN 0-632-03488-2.