Names of small numbers

This article lists and discusses the usage and derivation of names of small numbers.

Table of names

The following table lists English language names of small numbers used in the long and short scales, along with the power of 10, engineering notation, and International System of Units (SI) symbols and prefixes.

Power of ten	Engineering notation	Short scale (U.S. and modern British)	Long scale (continental Europe, archaic British, and India)	SI symbol	SI prefix
100	1	One	One
10−1	100×10−3	Tenth	Tenth	d	deci-
10−2	10×10−3	Hundredth	Hundredth	c	centi-
10−3	1×10−3	Thousandth	Thousandth	m	milli-
10−4	100×10−6	Ten-thousandth	Ten-thousandth		dimi-
10−5	10×10−6	Hundred-thousandth	Hundred-thousandth
10−6	1×10−6	Millionth	Millionth	µ	micro-
10−9	1×10−9	Billionth	Milliardth	n	nano-
10−12	1×10−12	Trillionth	Billionth	p	pico-
10−15	1×10−15	Quadrillionth	Billiardth	f	femto-
10−18	1×10−18	Quintillionth	Trillionth	a	atto-
10−21	1×10−21	Sextillionth	Trilliardth	z	zepto-
10−24	1×10−24	Septillionth	Quadrillionth	y	yocto-
10−27	1×10−27	Octillionth	Quadrilliardth	x	xona-
10−30	1×10−30	Nonillionth	Quintillionth	w	weco-
10−33	1×10−33	Decillionth	Quintilliardth

See also

• Names of large numbers
• Orders of magnitude (numbers)
• List of numbers § Small numbers
• List of arbitrary-precision arithmetic software