Before Mount Everest was discovered, what was the highest mountain in the world?

You have a square. What you have to do is cut and reassemble the square such that you create a Red Cross sign that has the same volume as that of the square.

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

Using mathematical symbols like +, -, and x in order to make the equations correct. Replace # with the above-given symbols.

9 # 8 # 7 # 6 # 5 # 4 = 91

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

What makes this number unique: 8,549,176,320?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

You are given four results as below:
1111 = F
2222 = E
3333 = T
Then, can you find out how to code 4444?

How many people must be gathered together in a room, before you can be certain that there is a greater than 50/50 chance that at least two of them have the same birthday?

A King wants to send the diamond ring to his girlfriend securely. He got multiple locks and their corresponding keys. His girlfriend does not have any keys to these locks and if he sends the key without a lock, the key can be copied in the way. How can King send the ring to his girlfriend securely?