Leena cut small cubes of 3 cubic cm each. She joined it to make a cuboid of length 10 cm, width 3 cm and depth 3 cm. How many more cubes does she need to make a perfect cube?

• volume of cuboid is 10*3*3=90
  volume of perfect cube is 10*10*10=1000
  because the maximum dimension is 10 to get cube all dimansions are equal i.e.,10
  to get perfect cube,no fo small cubes needed= volume of perfect cube- volume of given cuboid
  i.e.,1000-90=910.
  I think it is right
• 13 years agoHelpfull: Yes(64) No(39)
• volume of small cube is 3 cm3 it is given
  so total no of small cubes we have to make cuboid =10*3*3/3=30
  now we have to make a perfect cube by adding more cubes...
  by checking the option......
  if we put 8 cubes at 8 corner of cube which we have to make;;
  then no, of cubes required +(30-8) should be divisible by 12(ther should be 12 lines to make a cuboid )
  now at each line there should be equal no of cubes
  so (650+22) is completely divisible by 12....
  and other not so
  ans is 650.......
• 12 years agoHelpfull: Yes(3) No(18)
• Since length is 10cm,to make a cube she needs to make width and height to 10 cm. She needs 7 more for width but 1 face of width is partially covered by length on both sides. So she needs 7*(7-2) = 35 for width. For depth also she needs 7. But after filling width, see that both sides of depth are also covered. So she needs (7-2)*(7-2) = 25 for depth. so a total of 35 + 25 = 60 cubes of 1cm are needed. But cubes are of 3cm so 60/3 = 20 cubes is ans.
• 13 years agoHelpfull: Yes(2) No(27)
• All the options are wrong.
  10*10*10 = 1000
  10*3*3= 90
  left volume = 1000-90=910
  small cube volume = 3*3*3=27
  so no. of small cube is needed = 910/27 ~= 34
• 7 years agoHelpfull: Yes(2) No(1)
• Are you sure they are small cubes of 3 cm³ and not of 1 cm³ each ?
  In case the volume is 3 cm³ , the side is ∛3 and you cannot obtain 10 or 3 ( or any rational number by joining any number of such cubes ) ;
  
  I think it is V = 1 cm³ , then the side is 1 cm ;
  
  The volume of the cuboid is 10×3×3 = 90 cm³ ;
  To make a perfect cube it would be 10×10×10 = 1000 cm³
  
  The difference is 910 cm³ , and thus are 910 more small cubes required
• 6 years agoHelpfull: Yes(0) No(0)