Let's say there is a cube sitting in the first octant. Our F(x,y,z): <ax , by, cz> and Each face of the cube is oriented to outward pointing normal. Can I just calculate the the flux of one face and then multiply this by the number of faces to get the total flux? Will flux in a cube always be symmetric? I think you can parametrize a face by letting G(x,y,z)=<x,y,1>. Then use this to find normal and dot this with F(x,y,z) and integrate with dx dy with x and y ranging from where the sides start to where they end? I'm not sure. Please Help.