125 identical cubes are arranged in the form of a cubical block. How many cubes are surrounded by other…
125 identical cubes are arranged in the form of a cubical block. How many cubes are surrounded by other cubes from each side?
27
25
21
18
Solution
125 cubes form a $5 \times 5 \times 5$ block. The cubes completely surrounded on all sides form the inner block of size $(5-2) \times (5-2) \times (5-2) = 3 \times 3 \times 3 = 27$ cubes.