Problem 8 · 2014 Math Kangaroo
Medium
Geometry & Measurement
spatial-reasoning
George builds the sculpture shown from seven cubes, each of edge length 1. How many more of these cubes must he add to the sculpture to build a large cube of edge length 3?
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Answer: E — 20
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Hint 1 of 2
How many unit cubes does a 3×3×3 cube contain?
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Hint 2 of 2
Subtract the seven cubes he already has from the full count.
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Approach: count and subtract
- A cube of edge 3 is made of 3 × 3 × 3 = 27 unit cubes.
- He already has 7, so he needs 27 − 7 = 20 more.
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