Problem 14 · 2009 Math Kangaroo
Hard
Spatial & Visual Reasoning
spatial-reasoningcareful-counting
Thomas has made a table out of small cubes. How many small cubes did he use?
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Answer: D — 32
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Hint 1 of 3
Break the table into two easy parts: the flat top slab and the four legs underneath.
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Hint 2 of 3
Count the cubes in the top all by itself, then count one leg and notice every leg is the same size.
Still stuck? Show hint 3 →
Hint 3 of 3
Don't forget the cubes hiding behind the ones you can see.
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Approach: count the flat top, then add the four matching legs
- First just the flat top: it is a block 4 cubes long and 4 cubes wide, which is 4 × 4 = 16 cubes.
- Now the legs: there are 4 legs, one at each corner, and each leg is a stack of 4 cubes, so the legs are 4 × 4 = 16 cubes.
- Add the top and the legs: 16 + 16 = 32, remembering the back cubes you cannot see.
- So Thomas used 32 cubes.
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