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?

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

The day after tomorrow will be three days before Tuesday. Can you find out what is today?

I am a normal creature, but I have five hands. I can even have more but even then I will be considered normal.

Who am I?

Can you count the number of triangles inside a triangle?

The following sentence is false. The preceding sentence is true.
Are these two sentences true or false?

Consider this about a word: The first two letters signify a male, the first three letters signify a female, the first four letters signify a great, while the entire world signifies a great woman. What is the word?

I can be cracked, made, told, and played. What am I?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.