Say you're at a well and you need to collect 4 gallons of water. You have a five gallon bucket and a three gallon bucket. How do you preceed?
Easy mode: you have two five gallon buckets and three gallon bucket.
Both solutions will be posted at Puzzle #2.
Solution to Puzzle #0
I just realized I made a mistake in Puzzle #0. You would need to know if the counterfeit coin is heavier or lighter. My bad. In the first weighing you compare 3 coins to 3 other coins. If the balance is the same, then the counterfeit can be found by weighing the remaining two. Else you would compare two coins of the lighter group (say if they counterfeit was lighter). If one of the coins is lighter then you've found it. Else, the remaining coin is the counterfeit.