Problem 16 · 2021 Math Kangaroo
Hard
Arithmetic & Operations
sum-constraint
The kangaroo had two branches for lunch. Each branch had 10 leaves. The kangaroo ate some leaves from one branch. Then, from the second branch, it ate as many leaves as were left on the first branch. How many leaves in total were left on the two branches?
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Answer: D — 10
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Hint 1 of 3
Whatever is LEFT on the first branch is exactly what gets EATEN from the second branch.
Still stuck? Show hint 2 →
Hint 2 of 3
Try a number: if 4 leaves are left on branch one, the kangaroo eats 4 from branch two.
Still stuck? Show hint 3 →
Hint 3 of 3
Count the leaves still left on both branches and look for a pattern.
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Approach: the leftover from one branch is eaten from the other
- Whatever is left on the first branch, the kangaroo eats that same number from the second branch.
- So the leaves eaten from branch two exactly match the leaves still on branch one.
- That leaves one full branch worth in total: 10 leaves.
Mark:
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