Problem 15 · 2025 Math Kangaroo
Stretch
Logic & Word Problems
gridcasework
Amir has stickers of ladybugs with 1, 2, 3 or 4 dots on their wings. He fills the grid so that every row and every column has a ladybug with 1, 2, 3 and 4 dots. What should the top row of the grid look like when he is finished?
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Answer: B
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Hint 1 of 3
In every row and every column you must use a 1-dot, 2-dot, 3-dot and 4-dot ladybug, each exactly once.
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Hint 2 of 3
Look down each column at the ladybugs already placed to see which dot-numbers are still missing.
Still stuck? Show hint 3 →
Hint 3 of 3
A top cell must hold the one dot-number its column does not have yet.
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Approach: fill the grid so every row and column has 1, 2, 3 and 4 once
- Every row and every column must show a 1-dot, 2-dot, 3-dot and 4-dot ladybug, each just once.
- Look down each column and find the one dot-number it is still missing — that number must go in the top cell.
- Filling each top cell with its column's missing number gives the row shown in option B. The answer is B.
Mark:
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