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?

What has 13 hearts but no other organs?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

Identify the 10 differences between the two given pictures.

I’m tall when I’m young, and I’m short when I’m old. What am I?

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost every person. What am I?

I never was there, I am always to be.
You have never ever seen me, not ever you will.
Yet I am the confidence of everyone.

Who Am I?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?