If eleven plus two equals one, what does nine plus five equal?

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

You have 10 balls with you. A friend of yours out of nowhere asks you to place those ten balls in five lines such that each of the lines has exactly 4 balls on them. He needs to check your intelligence. Prove him by doing the task.

Can you place six X (crosses) in below board without making three in a row in any way ?

Can you find out which number multiplied by itself will give the output as 12345678987654321?

What does this rebus photo means?

In a chess board, the queen piece can move horizontally, vertically and diagonally freely. The picture represents the same.Can you place 8 queens on the board in a manner that none of the queens can attack each other?

I make two people out of one. What am I?

Chef Andrea has to light the kitchen stoves to open her restaurant for the day. There are three stoves in the kitchen: A glass stove, a brick stove, and a wood stove. She only has one match. Which does she light up first?

There are are five things wrong with this sentence; only geniuses will be able to to spot all of the mitstakes