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?

The more it dries, the wetter it becomes. Can you tell what it is?

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?

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

What Time Should the last watch show in the below figure?

Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I am double, I am single,
I am black blue and grey,
I am read from both ends,
And the same either way.

Can you find the key in the picture below?

It is always ahead of me yet I can never see it. What is it?

Count the Triangle in the figure given below:

Find the number of squares in the below picture