Question: You create your own Where's Waldo game on a piece of paper. You want your friend to find Waldo but they think you might be pulling a prank on them by not putting Waldo on the paper at all.
How can you prove to your friend that Waldo is on the paper without ruining it for them?
Answer: Cut a small hole in a piece of paper that is just large enough to see Waldo. This way you don't reveal anything about where he is, just that he is there.
Question: Man walks into a store and says to the shop owner: “I will spend $10 in your store if you double the amount of money I now have in my pocket.” Store owner agrees; doubles his money; he spends $10 and leaves. He repeats this at 2 more stores. When he leaves the 3rd store he has $0 dollars. How much money did he have in his pocket when he walked into the first store?
Answer: You have to solve this starting with the last store. This means he walked into the 3rd store with $5, had it doubled to $10 and spent the whole $10. He entered the 3rd store with $5.00. He spent $10, so he had $15 after his money was doubled. $15 / 2= Means he had $7.50 when he entered the 2nd store. He left the 1st store with $7.50. He spent $10 so he had $17.50 after his money was doubled; $17.50 divided by 2. So, he started out with $8.75 when he walked into the first store.