The more of this there is, the less you see. What is it?

Can you count the number of quadrilaterals in the picture below?

Replace the question mark with the correct number in below Picture:

What happened when the wheel was invented?

Your last good ping-pong ball fell into a narrow metal pipe embedded one foot deep in concrete.
How can you get it out undamaged, if all the tools you have are your tennis paddle, shoe laces, and plastic water bottle, which does not fit into the pipe?

We can be boring,Or interesting.
We can be long,Or short.
We can have pictures,Or just words.
Many love us,But many also hate us.
What are we?

Can you find out the next digit in the following series ?

0, 0, 1, 3, 2, 6, 3, 9, 4, 12, 5, ?

I am a type of room you cannot enter or leave. Raised from the ground below, I could be poisonous or a delicious treat. What am I?

By including only four matchsticks in below picture, you have to make "Four Triangles And Two Squares"

Can you spot the hidden girl in the picture below?