Move four matchsticks to the below square to form three squares?

Can you find out which triangle will have a bigger area among the following?
1. A triangle with sides 300, 400 and 500
2. A triangle with sides 300, 400 and 700

You are given with the following sum. Each of the letters can be decoded as a digit. If we tell you that D = 5, then can you solve it entirely?

DONALD
+GERALD
=ROBERT

Can you count the number of rectangles on a chessboard?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?

I know a number which is spelt in alphabetical order.
Do you?

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?

Can you make a fire with just a single stick?

How many words can a pen with half refill write?

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.