Can you find out the missing number?

? 4 5 3 5

9 5 7 10 3

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

Why do you find that most of the buildings are deprived of the 13th floor?

I can write cow in 13 letters.

Can You?

Find the hidden tiger in the given optical illusion ?

John can eat 27 chocolates in an hour, Jacob can eat 2 chocolates in 10 minutes, and Jolly can eat 7 chocolates in 20 minutes. How long will it take them to share and eat a box of 120 chocolates whilst playing Chess?

Can you move 2 matchsticks to form four equal sized squares.

Four men were in a boat on the lake. The boat turns over, and all four men sink to the bottom of the lake, yet not a single man got wet! Why?

You need to complete the maze by entering from the entrance marked below in the figure near the yellow circle, bottom left and leaving from the exit point near the green circle, bottom middle.

Rule of Game: You can move only by exchanging green and yellow circles.

A boy and a girl are sitting on the porch.
"I'm a boy," says the child with black hair.
"I'm a girl," says the child with red hair.
If at least one of them is lying, who is which?