How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

You are presented with three boxes. One of them has a red ball inside and the other two have a black ball inside each of them. You are asked to pick up the one with red ball and you pick one. Now, one of the other boxes is opened and it is found to have a black ball.

You are presented with a chance to change your box with the one that is left closed. Will you change your box? Why or why not?

There is a place where if I stand up straight, I will still be considered sideways.

How many times can you subtract the number 5 from 25?

Chhote se Chintu Miyan,
Lambi si Pooch.
Jahan Jaye Chintu Miyan,
Wahan Jaye Pooch.

छोटे से चींटू मियाँ,
लंबी सी पूंछ।
जहाँ जाये चींटू मियाँ,
वहाँ जाये पूंछ।

Bolo kya?

Why Wine Glass Stem is so long?

Place a mathematical symbol between the numerals 5 and 9 in such a way that the resulting number is greater than 5 but smaller than 9.

What do you see in the given picture?

Count the number of triangles in the below picture?