Page 155 - NUMINO Challenge_D2

Answer
Key

8 Cubes and Surface Area p.68~p.69 2 There are (9 8 8) 2 50 sides that can be

Example 5, 2, 32 2 34 seen from the top and bottom, front, and back,
and right side and left side.
Example 2, 8 6, 24 12, 24 8 The number of sides that cannot be seen is 8 on
the 3rd floor, and 4 on the 2nd floor, which is
Type 8-1 Surface Area of a Cube with Holes p.70~p.71 12 sides in total. Therefore, there are
50 12 62 sides that are colored and since the
1 8 6 48 faces area of one side is 1 cm2, the surface area is 62
2 4 faces cm2. Draw the shape of each floor as shown
3 4 6 24 faces below and write the number of colored sides.
4 48 24 72 faces
5 72 cm2 323 232 55

222 3 3 55
3rd Floor
323 232
(20)
1st Floor 2nd Floor
(22) (20)

22 20 20 62 cm2

Problem solving Type 8-2 Unchangeable Surface Area p.72~p.73

1 1 0, 2, 4

Top Front Right Side 2 3 Faces

3 There are 7 cubes that can be removed which
include 6 colored blocks as shown below, and
one cube added at the vertex of the first floor,
which cannot be seen.

Since the stickers will not be put on the floor, the Problem solving
number of sides viewed from the top will not be
doubled, but only the number of sides viewed 1
from the front and side. All sides can be seen
from these shapes.

7 (8 8) 2 39 stickers are needed.

There are 4 ways.

NUMINO Challenge D2