Your back. You have one and it’s easy to touch but hard to look it. A common phrase is to “watch your back” and it’s common to “have your friend’s back.” When apologizing, you often want to take back what you said. You can throw out your back, but you can’t throw it away. And back pain causes people pain every day.
This problem can be solved by preschool children in five to ten minutes, by programmers in an hour and by people with higher education…well, check it yourself.
Yes, there’s a 4th of July in every country. Of course they don’t treat it as a holiday as citizens of the United States do, but that’s not what was asked.
A windmill. The typical windmill, like the ones Don Quixote chased, have four vanes or sails. You might even say they look like wings. Windmills don’t have emotions, so they can’t laugh or cry. And since they don’t have actual wings, windmills don’t get off the ground. A well-oiled little bugger won’t make a peep.
There are two tricks to this one. The first is 1 × 0. But it’s mostly there as a distraction. Yes, 1 × 0 is 0, but that doesn’t affect anything else in the equation. The second, far trickier element is that the lines ending with 1 don’t have a + sign next to them. That means they should be combined with the following line.
A merchant has 21 sacks of grain: 7 full, 7 half-full and 7 empty. He wants to divide them equally among his three sons. How can he do this, without transferring any grain between sacks, so each son has the same quantity of grain and number of sacks?
You are a spy and need to send an item to a contact in another country without letting anyone else have access to it. All unlocked items will be opened in transit. How can you send this item securely?
Place a lock on the item and send it to your contact. They will place their own lock on the package and return it to you. You remove your lock and send it back. When they receive it, they can unlock the package and retrieve the item.
