Numeral, Metric and Binary Prefixes

by Ibraheem Rodrigues

Uni, Bi, Kilo, Mibi etc.

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• Small Quantity Prefixes
  • IUPAC Names
• Metric and Binary Prefixes

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Small Quantity Prefixes

Quantity	Common Prefixes	IUPAC Standard (Chemical Names)1
$\frac{1}{2}$	Semi-, Demi-, Hemi-	N/A
1	Uni-, Mono-	Mono-, hen-
2	Bi-, Di-	Di-, do-
3	Tri-	Tri
4	Quad-, Tetra-	Tetra-
5	Penta-	Penta-
6	Sex-, Hex-	Hexa-
7	Sept-, Hept-	Hepta-
8	Oct-	Octa-
9	Nov-, Non-	Nona-
10	Dec-	Deca-
11	Undec-, Hendec-
12	Duodec-, Dodec-
13	Tredec-, Tridec-
20	Icosa-	Icosa-
100	Centi-, Hecta-	Hecta-
1000	Kilo-,	Kilia-
Few	Pauci-, Oligo-	N/A, Oligo- sometimes used
Many	Multi-, Pluri-, Poly-	N/A, Poly- sometimes used
All	Omni-	N/A

IUPAC Names ¹

For higher multiples of 10, 100 and 1000:

• 30, 40, 50 etc: Add -conta- (tetraconta-, pentaconta-)
• 300, 400, 500 etc: Add -cta- (tricta-, tetracta-)
• 2000, 3000 etc: Add -lia- (hexalia-, hexalia-)

To build numbers, join prefixes for each digit (replace mono- with hen- and di- with do-)

$$\begin{array}{cc}421=& 1+20+400\\ \to & \text{hen-, icosa-, tetracta-}\\ =& \text{henicosatetracta-}\end{array}$$

For complex features, -kis- is added:

• 5 = pentakis-
• 421 = henicosatetractakis-
• Note mono- remains unchanged, di- becomes bis- and tri- becomes tris-

Metric and Binary Prefixes

Metric Prefix2	Symbol	Factor	Factor	Symbol	Metric Prefix
Yotta	Y	${10}^{24}$	${10}^{-24}$	y	Yocto
Zetta	Z	${10}^{21}$	${10}^{-21}$	z	Zepto
Exa	E	${10}^{18}$	${10}^{-18}$	a	Atto
Peta	P	${10}^{15}$	${10}^{-15}$	f	Femto
Tera	T	${10}^{12}$	${10}^{-12}$	p	Pico
Giga	G	${10}^9$	${10}^{-9}$	n	Nano
Mega	M	${10}^6$	${10}^{-6}$	µ	Micro
Kilo	k	${10}^3$	${10}^{-3}$	m	Milli
Hecto	h	${10}^2$	${10}^{-2}$	c	Centi
Deca	da	${10}^1$	${10}^{-1}$	d	Deci

When used to denote a number of bits/bytes (kilobyte, megabit, etc.), there is some ambiguity as whether these units refer to a multiple of ${10}^3=1000$, as above, or a multiple of $2^{10}=1024$. The IEC defines the following Binary Prefixes in an attempt to alleviate this issue, although adoption is ultimately implementation dependent.

Binary Prefix3	Symbol	Factor
Yobi	Yi	$2^{80}$
Zebi	Zi	$2^{70}$
Exbi	Ei	$2^{60}=1152921504606846976$
Pebi	Pi	$2^{50}=1125899906842624$
Tebi	Ti	$2^{40}=1099511627776$
Gibi	Gi	$2^{30}=1073741824$
Mebi	Mi	$2^{20}=1048576$
Kibi	Ki	$2^{10}=1024$