What is the riddle which can be asked all day with a different correct answer each time.

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

Can it be possible to build a house that has all its four walls facing towards the South?

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?

Rob is taller than Edwin, and Jurgen is shorter than Rob.
Of only one of the following statements, we now certainly know it is correct:

A.Edwin is taller than Jurgen
B.Jurgen is taller than Edwin
C.It cannot be determined if Jurgen or Edwin is the tallest.

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

If an electric train is travelling south, then which way is the smoke going?

What does does this rebus picture means ?

In the image below, you can see two glasses and two matchsticks.You need to move four matchsticks in such a manner that the crosses come inside the glasses. Note: you cannot move the crossed.

In a school, there are four subjects. Seventy percent of students study English, seventy five percent of students study Science, eighty five percent of students study Mathematics and eighty percent of students study Spanish.

Can you calculate the percentage of students that study all four subjects?