10
SI is a base 10 standardized system
No, of 10.
10
They are related to larger and smaller units by powers of ten near the basic unit and by powers of 1000 further away.
The metric, or SI system of measurement is based on units which, in most cases, are related to larger or smaller units by multiples or factors of ten. The exception is time where the factors are 60.
The prefix is used for the name of multiples and submultiples.
http://physics.nist.gov/cuu/Units/units.html
A2. The base units in the SI system are metre, kilogram, second, ampere, kelvin, candela, and mole.A1. Giga, mega, kilo, milli, micro, pica [A2 note these are a few of the multiples or sub-multiples.]
The SI system is based on multiples (and divisions) of ten. There are seven base units, all others are derived from these.
There are seven SI base units. Refer to the related link below for a table of the seven SI base units.
Yes, it can. The units are kg/m3, or related versions.