We all love a good puzzle, and if you’re like me, calling it “unsolvable” only makes you more determined to figure it out. That said, these are actually really hard. Like, really hard.

Photo Credit: Warner Bros.

Like, if you figure them out without looking, you’re way smarter than me. Give it a shot!

#1. A Locked Door

You have 100 bags of coins each with 100 coins, but only one of these bags as gold coins. The gold coin weighs 1.01 ounce and the other coins weigh 1 ounce. You also have a scale, but can only use it once. How can you identify the bag of gold coins?

Photo Credit: Warner Bros.

#2. The Burning Ropes

You can given two ropes and a lighter. Each of the two ropes has the following property: if you light one end of the rope, it will take exactly one hour to burn to the other end. It doesn’t necessarily burn at a uniform rate. How can you measure a period of 45 minutes?

Photo Credit: Instagram, mizlinasuh

#3. Glass Half Full

You are in an empty room with a transparent glass of water. The glass is a right cylinder and appears to be half full. How can you accurately figure out whether the glass is half full, more than half full, or less than half full? You have no rulers or writing utensils.

Photo Credit: Pixabay

#4. Cork, Bottle, Coin

You put a coin in an empty bottle and insert a cork in the bottle’s opening. How can you remove the coin without taking out the cork or breaking the bottle?

Photo Credit: Instagram, atelier.aqualily

#5. Global Trek

How many places are there on earth where one could walk one mile south, then one mile west, then one mile north and end up in the same spot? The earth is a solid, smooth sphere.