You need to be clear about what you're trying to convert, and what you expect it to mean. "mass" per "volume", as in grams or kilograms per cubic centimeter or cubic meter, is a measure of

"Kilo-" is a prefix meaning 1000. "Centi-" is a prefix meaning 1/100.

1 kg = 1000 g

1 cm = .01 m

Otherwise, you can treat the units of measure as you would any variable. You can multiply and divide them as you need to do the conversion you want.

(10.5 g)/(50 cm^2)

= .21 g/cm^2

= (.21 g/cm^2)*(1 kg/(1000 g))*(100 cm/m)^2

= 2.1 kg/m^2

*density*, an intrinsic property of material. "mass" per "area", as in grams or kilograms per square centimeter or square meter, is a measure of*areal loading*--not the same as density. One can only be converted to the other if you know the volume of material involved and the area over which it is spread."Kilo-" is a prefix meaning 1000. "Centi-" is a prefix meaning 1/100.

1 kg = 1000 g

1 cm = .01 m

Otherwise, you can treat the units of measure as you would any variable. You can multiply and divide them as you need to do the conversion you want.

(10.5 g)/(50 cm^2)

= .21 g/cm^2

= (.21 g/cm^2)*(1 kg/(1000 g))*(100 cm/m)^2

= 2.1 kg/m^2