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2014 Math Kangaroo

Problem 13

Problem 13 · 2014 Math Kangaroo Hard
Spatial & Visual Reasoning paper-cuttingtiling-tessellation

A square is cut into four pieces. Which shape can you not make with these four pieces?

Figure for Math Kangaroo 2014 Problem 13
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Answer: D
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Hint 1 of 3
The four pieces never change, so every shape you build with them must take up the same amount of space as the square.
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Hint 2 of 3
Pretend the pieces are puzzle pieces and try to slide them inside each shape, turning and flipping as needed.
Still stuck? Show hint 3 →
Hint 3 of 3
Four of the shapes can be filled with no gaps; one shape always leaves a gap or an overhang.
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Approach: try to fit the same four puzzle pieces into each shape and find the one that won't go together
  1. The square is cut into four set pieces, so any shape made from all four covers exactly the square's worth of space.
  2. Treat the pieces like a puzzle and try to fill each answer shape, allowing turns and flips.
  3. Shapes A, B, C, and E can each be filled neatly with the four pieces.
  4. Shape D is the one that cannot be built from these four pieces.
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