Three solid cubes of sides 1 cm, 6 cm and 8 cm are melted to form a new cube. Find the surface area of the cube so formed

Volume of new cube =   $13+63+83cm3$=  $729cm3$  

Edge of new cube =  $7293$ = 9cm

Surface area of the new cube = ( 6 x 9 x 9) sq.cm = 486 sq.cm