Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

A man lives on the fifteenth floor of an apartment building. Every morning he takes the elevator down to the lobby and leaves the building. In the evening, he gets into the elevator, and, if there is someone else in the elevator, or if it was raining that day, he goes back to his floor directly. Otherwise, he goes to the tenth floor and walks up five flights of stairs to his apartment. Can you explain why he does this?

Which is the smallest number that you can write using all the vowels exactly once?

A mathematician couple was having a Frappuccino in Starbucks sitting opposite to each other. Suddenly the guy noticed the text written on the paper in front of them and exclaimed that it was wrong. The girl denied it and said it is appropriate. Both are correct. What is written on the paper?

You see a mathematical expression in the picture. Can you think of a movie that this expression refers to?

When 99 is considered higher than 100?

I am an odd number. Take away a letter and I become even. What number am I?

What always comes into a house through the keyhole?

What is at the end of a rainbow?

Can you find out the total number of triangles in the given figure?