Can you count the number of triangles in the given picture?

Which is heavier: a ton of bricks or a ton of feathers?

You are given 16 witch hats. The hats are divided in four different colours – red, blue, green and yellow. Every colour has been assigned to four hats. Now each of the hat will be glued with a label of an arithmetic sign – ‘+’, ‘-‘, ‘x’ or ‘/’. But you can label one sign only once on one colour. In such an arrangement, the hats can be uniquely defined by its colour and symbol.

Can you arrange all the 16 hats in a 4x4 grid in a fashion that no two rows and columns have a repetition of colour or sign?
We have arranged four hats in the below picture to assist you.

There is a shop where written:
Buy 1 for $1
10 for $2
100 for $3
I needed 999 and still only paid $3. How could this be financially viable for the shop-keeper?

Can you count the number of triangles inside a triangle?

You see a mathematical expression in the picture. Can you think of a movie that this expression refers to?

There's a day, that comes around once a year.
To celebrate the man, you hold dear.
He gave you life, love and will pick you up if you fall.
When it comes to guys like him, He's the best of all.
Who is he?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

What is wrong in the below Picture?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?