Question

A large cube is formed with 64 white unit cubes. If all sides of the big cube are painted black, how many white unit cubes will be unaffected in the end?

Answer 1

Question

A large cube is formed with 64 white unit cubes. If all sides of the big cube are painted black, how many white unit cubes will be unaffected in the end?

Answer

STEP 1

Draw a cube first

STEP2

NOW LOOK AT FIG

HERE, 4 layer when we go from upper to lower

1 layer=>

all cube are painted with white colour

=>so 0 cubes are unaffected

2 layer=>

cubes which at the edge are painted

=> 4 cubes in center are unaffected

3layer

similarly to 2nd

cubes which at the edge are painted

=> 4 cubes in center are unaffected

4 layer=>

all cube are painted with white colour

=>so 0 cubes are unaffected

Hence number of unaffected cubes

=0+4+4+0

=8Ans