Mathematical Brain Teasers and Logic Puzzles

Brain teasers are fun and popular activities for all ages and all levels of reasoning skill. For example, here’s a good one: A man goes into a store to buy a certain item. The clerk tells him the item costs 25¢ each. The man replies, “Great, I’ll take 100.” The clerk charges him 75¢. What was the man buying? Here, the solution involves thinking outside the box, in which you approach the problem from a new perspective, often by paying close attention to ambiguity in how the problem is stated. Thinking outside the box is a great strategy for many situations in life. Here’s another: On the Island of Knights and Knaves, knights always tell the truth and knaves always lie. Two residents of the island walk up to you and one says, “Both of us are knaves.” What can you conclude? This is a classic logic exercise, requiring you to sort through different possibilities and deduce what must be the case, given the information available.