Problem 4 · 2025 Math Kangaroo
Easy
Geometry & Measurement
grid-countingcomplementary-counting
Felix forms a square out of 16 small, grey tiles. He then removes some of the small tiles — see picture. How many small tiles did he remove?
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Answer: C — 6
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Hint 1 of 3
The empty spots are where tiles used to be — you can count those directly.
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Hint 2 of 3
A full 4-by-4 square holds 16 tiles in all.
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Hint 3 of 3
Count the grey tiles that are still there, then see how many are missing from 16.
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Approach: count what remains, then subtract from the total
- The full square has 4 × 4 = 16 small tiles.
- Count the grey tiles still in place: there are 10 of them.
- Removed tiles = 16 − 10 = 6.
Mark:
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