The idea
Plan, front and side views show a solid from one direction at a time.
Follow these steps
- Choose the viewing direction.
- Project occupied positions onto that view.
- Use visible heights or layers without counting hidden cubes twice.
See the method in action
Example 1
The plan view uses a 3 × 3 floor grid. How many positions are occupied, and how many are empty?
View from above required
- First count one top square at each occupied floor position: 6.
- Then subtract from the 3 × 3 grid: 9 − 6 = 3 empty positions.
Example 2
The plan view uses a 3 × 3 floor grid. How many positions are occupied, and how many are empty?
View from above required
- First count one top square at each occupied floor position: 3.
- Then subtract from the 3 × 3 grid: 9 − 3 = 6 empty positions.
A useful shortcut
Use visible heights or layers without counting hidden cubes twice.
Watch out for these
Three fresh questions
Ready to check the method? You will get three fresh, validated questions.