1.5 Prefixes to Power of Ten

A mechanism through which numbers are expressed in powers of ten that are given a proper name is called a prefix. Prefixes make standard form or scientific notation further easier. Large numbers are simply written in more convenient prefixes with units. For example, the thickness of a paper can be written conveniently in smaller units of millimetre instead of metre. Similarly, the long distance between two cities may be expressed better in a bigger unit of distance, i.e., kilometre. Some prefixes in SI to replace powers of 10 are given in the table below.

TABLE 1.3: Prefixes

Decimal Multiplier	Prefix	Symbol
10^18	Exa	E
10^15	Peta	P
10^12	Tera	T
10^9	Giga	G
10^6	Mega	M
10^3	Kilo	k
10^2	Hecto	h
10^1	Deca	da
10^-1	Deci	d
10^-2	Centi	c
10^-3	Milli	m
10^-6	Micro	μ
10^-9	Nano	n
10^-12	Pico	p
10^-15	Femto	f
10^-18	Atto	a

Examples

The number of seconds in a day is: 86,400 seconds = 8.64 x 10^4 s = 86.4 ks.
The distance to the nearest star, Alpha Centauri, is: 4.132 x 10^16 m = 41.32 Pm.
The thickness of the page of this book is about: 4.0 x 10^-4 m = 40 x 10^-3 m = 40 mm.
The mass of a grain of salt is: 1.0 x 10^-4 g = 100 x 10^-6 g = 100 mg.

Do You Know?

Volume is a derived quantity:

1 L = 1 dm³ = (10 cm)³ = 1000 cm³
1 mL = 1 cm³

Can You Tell?

The mass of the Sun is about 1.97 x 10^30 kg.
The radius of a hydrogen atom is about 0.00000000005 m = 5 x 10^-11 m.
The age of the Earth is about 143,300,000,000,000,000 s = 1.433 x 10^17 s.

Can You Express?

The thickness of a sheet of paper is about 100,000 nanometers = 1 x 10^5 nm = 1 x 10^-4 m.
Pakistan has a total installed power generation capacity of over 40,000 megawatts = 4 x 10^4 MW.
A single hard disk capacity of computers has exceeded 30 terabytes = 30 x 10^12 bytes.