A math problem: There are two buckets, one is 5 liters and the other is 6 liters. How can I make 3 liters of water?
Fill the 6-liter barrel first, and then pour it into the 5-liter barrel. After filling up, there is 1 liter left in the 6-liter barrel. Pour out the water in the 5-liter bucket, pour 1 liter into the 6-liter bucket, and then pour the 6-liter bucket full of water into the 5-liter bucket. Because there is 1 liter in a 5-liter barrel, it is 6 liters when it is full.