Three balls of masses $2 \mathrm{~kg}, 4 \mathrm{~kg}$ and 6 kg respectively are arranged at centre of the edges of an equilateral triangle of side 2 m . The moment of inertia of the system about an axis through the centroid and perpendicular to the plane of triangle, will be $\_\_\_\_$ $\mathrm{kg} \mathrm{m}^2$.