You have a 3 liter container and a 5 liter container, neither of which have any markings. Using an unlimited supply of rootbeer, explain how one could use just these two containers and end up with exactly 4 liters of root beer.
You may not use any estimating but by simply pouring in and out and throwing some away, you will succeed. What is the least number of steps you can do this in?
All you have to do is draw this out exactly and show step by step how this is done. Your drawings and steps should be very neat and precise.
Under comment describe how you finally figured it out and what logic you used.
When done try the link on the bottom of this page for another fun one.