Answered By Clifton P

For this sort of problem we need to look at how many grams are in a kilogram and how many centimeters are in a meter. 

We have 1000g/kg, or 1kg/1000g

and 100cm/m. One tricky bit is we’re dealing with cm^3 and m^3 tho, so we need to cube the 100cm/m,

ie (100cm/m)^3

This gives us 10^6cm^3/m^3

now that we have our conversion factors, we can apply them to our given value. 

(2.31x10^8g/cm^3)*(1kg/1000g)*(10^6cm^3/m^3)

its harder to see in the text here, but when written out the units should line up such that they can cancel out, leaving only the units we want in the end. 

(2.31x10^8)*(10^6/10^3) (g*kg*cm^3/g*cm^3*m^3)

the g and cm^3 are on both the top and bottom, canceling out, leaving the kg/m^3

10^6/10^3 simplified to 10^3 (remember your exponent laws)

so, 2.31x10^8 * 10^3 gets us 2.31x10^11kg/m^3

hope that helps :)

Answered By Majid B

 $2.31\times10^8\left(\frac{gr}{cm^3}\right)=2.31\times10^8\left(\frac{0.001kg}{\left(0.01m\right)^3}\right)=2.31\times10^8\times\frac{0.001}{\left(0.01\right)^3}\left(\frac{kg}{m^3}\right)=2.31\times10^8\times\frac{10^{-3}}{\left(10^{-2}\right)^3}\left(\frac{kg}{m^3}\right)=2.31\times\frac{10^5}{10^{-6}}\left(\frac{kg}{m^3}\right)=2.31\times10^5\times10^6\left(\frac{kg}{m^3}\right)=2.31\times10^{11}\left(\frac{kg}{m^3}\right)$2.31×10⁸(grcm³ )=2.31×10⁸(0.001kg(0.01m)³ )=2.31×10⁸×0.001(0.01)³ (kgm³ )=2.31×10⁸×10⁻³(10⁻²)³ (kgm³ )=2.31×10⁵10⁻⁶ (kgm³ )=2.31×10⁵×10⁶(kgm³ )=2.31×10¹¹(kgm³ )