First off, I am glad to be a newbie to the forum. I am a freshman at Colorado State University who is undeclared with a mechanical engineering concentration. In my Chemistry 111 class, I have been practing a practice test online, but the last problem I can't get right. Can anybody show me how to do it? Don't worry about cheating or anything, it is only a practice test and not worth any points. Question: A silicon atom-diameter 2.7X10 to the negative 10 meters, and a mass of 4.7X10 to the negetive 23rd grams. they are packed into a cube. What is the length of the cube formed by 1000kg of silicon atoms, packed this way? the answer is 0.75 meters, but I can't get there, is the problem.