## Task 1 - 220611

In an aquarium, the hollow space that could be filled with water has the shape of a cube with a side length of $60 \mathrm{~cm}$. However, this hollow cube is to be filled only up to a height of $10 \mathrm{~cm}$ below its upper edge.

How many buckets of water are required in total if each bucket holds 9 liters?
Due to $60-10=50$, the part of the aquarium to be filled with water has the shape of a cuboid with a volume of $60 \mathrm{~cm} \cdot 60 \mathrm{~cm} \cdot 50 \mathrm{~cm}=180000 \mathrm{~cm}^{3}=180 \mathrm{dm}^{3}$.

Since 1 liter of water has a volume of $1 \mathrm{dm}^{3}$, it follows that 180 liters of water need to be filled. Since $180: 9$ $=20$, this is exactly 20 buckets of water.