What's the only room from which no one can enter or leave

Count the number of triangles in the picture below:

This is a classy optical illusion puzzle. What more you can find except bricks in the image below?

In the city of Brain Teasers, 5% of people do not list their phone numbers. Now if we select random 100 people from the phone directory, then how many people selected will have unlisted phone numbers?

In a mathematical quiz, you are asked the following question:

Use three 9s in a mathematical expression without dividing or multiplying to form the number one.

Can you answer the question?

Manish has to secure 40% marks to pass his B.tech final exams.
He got just 40 marks and failed by 40-marks.

What is the maximum marks?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

You need to pick one entry from pot A and one from pot B to have a perfect match. Can you do it?

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

Rose, Lily and Jasmine decided to buy flowers for their moms on Mother's Day. One of them bought lilies, the other roses, and the third one jasmines.
'It's funny!' said the girl with roses, 'we bought roses, jasmines and lilies, but none of us bought the flowers matching her name'.
'You're right!', said Lily.
What kind of flowers did each of the girls buy?