the prefixes tell you how much bigger or smaller a unit is than the base unit e.g. one KILOmetre is one thousand metres
tera (T)
1012
giga (G)
109
mega (M)
1,000,000 (106)
kilo (k)
1000
deci (d)
0.1
centi (c)
0.01
milli (m)
0.001
micro (μ)
0.000001 (10-6)
nano (n)
10-9
to get from a bigger unit to a smaller unit,
…you multiply the conversion factor
to get from a smaller unit to a bigger unit,
…you divide by the conversion factor