The volume would increase by the cube of the linear dimensions. That is, L³ = 10³ = 1000. Consequently, the legs would have to be 1000 times as strong as before.
The legs can be considered as pillars (or cylinders), and the strength of a pillar is dependent on its area. To be 1000 times as strong the legs must therefore have 1000 times the area as before.
To achieve this, the diameter of the legs would have to increase by what factor?