Chemistry
posted by Lisa .
The density of aluminum is . A square piece of aluminum foil, 20.02 on a side is found to weigh 2.573 .What is the thickness of the foil, in millimeters?

You didn't provide the density.
20.02 what?
2.573 what?
We just went through this you first post. You should catch on soon that these problems don't mean a thing without units.
If I weigh 150 WHAT that could be 150 pounds, 150 kg, 150 tons, 150 grams. 
when I was copying and pasting the problem the units and numbers did not transfer... I completely understand that you need these units

The density of aluminum is 2.70 g/cm^3. A square piece of aluminum foil, 20.02 on a side is found to weigh 2.573g. What is the thickness of the foil, in millimeters?

20.02cm*

density = mass/volume. You have the mass and density, solve for volume, then substitute volume into the below equation and solve for thickness.
volume = length x width x thickness.
v = 20.02 x 20.02 x thickness. 
thank you

is the answer 4218.95 mm?