Samita was making a cube with dimensions 5*5*5 using 1*1*1 cubes. What is the number of cubes needed to make a hollow cube looking of the same shape? If we are painting only 2 face of each cube then how many faces will remain unpaint???

• Vol of the outside cube = 5*5*5=125
  Vol of the hollow part inside the outside cube = 3*3*3=27
  No.of cubes required to make a hollow cube of same shape= 125-27=98
  
  Total no of faces= 98*6=588
  No of faces painted=5*5*2=50
  No of faces that remain unpainted=588-50=538
  
• 12 years agoHelpfull: Yes(26) No(6)
• For a full 5*5*5 cube, we will use 5*5*5 = 125 cubes of size 1*1*1
  However, we are leaving the internal of the cube hollow.
  The internal of the cube is actually a cube of size 3*3*3
  To make such a cube, we need 3*3*3 = 27 cubes of size 1*1*1
  Thus, the number of cubes we need to make such a hollow cube will be:
  125 - 27 = 98 cubes of size 1*1*1
  
  
  For your second question, I assume you are talking about the faces of the 5*5*5 cube.
  Each cube, regardless of size, has 6 faces.
  Thus, the 5*5*5 cube will have 6 - 2 = 4 unpainted sides.
  
  If you are talking about the 1*1*1 cubes, since there are 98 of them, we will have:
  98*4 = 392 unpainted faces.
• 12 years agoHelpfull: Yes(25) No(14)
• can u plzz tell y is iit (5-2)??
• 12 years agoHelpfull: Yes(11) No(1)
• no of hollow cube === 5*5*5 - (5-2)*(5-2)*(5-2)
  === 98
  no of face unpainted === 392
• 12 years agoHelpfull: Yes(5) No(4)
• 538 is the answer
• 12 years agoHelpfull: Yes(3) No(3)
• can u explain answer.....
  
• 12 years agoHelpfull: Yes(2) No(2)
• for the second part of this question we have total 98 small cubes. total faces=98*6 =588 4 faces of large cube is unpaintad. area of each face for large cube = 25 area of each face of smaall cubes =1 , so in each face of large cube there are 25 face of small cubes. painted faces of small cubes = 25*2=50 unpaint faces 588-50=538
• 12 years agoHelpfull: Yes(2) No(2)
• 98 is the answer
• 12 years agoHelpfull: Yes(0) No(4)