What is the fastest way to double your money?

I add 5 to 9 and get 2. The answer is correct, so what am I?

The following four words might seem abrupt to you. But you can make them meaningful by just adding vowels.
RDSH
GGPLNT
TMT
NN

Hint: All of them are vegetables.

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

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

Can you find the odd one out from the below words ?

First Second Third Forth Fifth Sixth Seventh, Eighth Nine Ten Eleven Twelve.

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

In the attached figure, you can see a chessboard and two rooks placed on the chess board. What you have to find is the number of squares that do not contain the rooks. How many are there?

What does this mathematical rebus means ?

Can you place three balls such that the equation shown in the picture holds true?