a cube of gold 30mm long on each edge is worth $10,000.how much is a gram of gold worth?
Multiply 27 cm^3 (which is the volume) by the density of gold in g/cm^3, (which you should look up).
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That will give you the number of grams (the mass).
Divide $10,000 by that mass for the number they want.
That price per gram will be much less than today's value