Unit prefixes

You can insert a unit prefix in front of a unit to indicate a power of ten.
The following tables gives the available prefixes:

Prefix	Name	(*10^) n	Prefix	Name	(*10^) n
Y	yota	24	d	deci	-1
Z	zeta	21	c	cent	-2
E	exa	18	m	mili	-3
P	peta	15	mu	micro	-6
T	tera	12	n	nano	-9
G	giga	9	p	pico	-12
M	mega	6	f	femto	-15
k or K	kilo	3	a	atto	-18
h or H	hecto	2	z	zepto	-21
D	deca	1	y	yocto	-24

Remark
You cannot use a prefix with a built-in unit if the result gives another built-in unit.
For example, 1_a is one are, but 1_Pa is one pascal and not 10^15_a.