If the length, breadth and height of a cuboid are all increased to 'n'times their original values of 'n'.

Explanation

Volume of the cuboid `="length "xx "breadth "xx " height "` volume of the new cuboid
`=(n xx" length") xx (n xx "breadth") xx (n xx "height")`
`=n^3 ("length "xx " breadth "xx " height")`
Density `=("mass")/("volume")`
`8/1=n^3/1, n^3=8, n=2`