Suppose you have ten trees. How can you plant these trees so that they form five rows of four trees each. Leave a comment if you figure out the answer.
If the first problem is tough, the second one is much tougher. How can you you do the same task (plant five rows of four trees) with only eight trees. It sounds impossible, and it is unless you use an imaginative approach. (Hints: Don't bother planting more than four trees in a row. The second problem is possible, but may not be practical.)