Can you think of any three-dimensional shape that comprises of exactly two surfaces?

There is a unique number which when multiplied by any number from 1 to 6, we will get the new number that contains the same digits only.

Can you find that number?

Can you divide the below-given shape into four equal and identical pieces?

Jim and Sarah are in a long-distance relationship. Jim buys an engagement ring for Sarah and wants to mail it to her. Unfortunately, the only way to ensure the ring will be received is to place a lock on the package. Jim has locks and Sarah has locks, but neither has keys for each other’s locks. How can they make sure the ring isn’t stolen?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

There was once a college that offered a class on probability applied to the real world. The class was relatively easy, but there was a catch. There were no homework assignments or tests, but there was a final exam that would have only one question on it. When everyone received the test paper it was a blank sheet of paper with a solitary question on it: 'What is the risk?'.Most students were able to pass, but only one student received 100% for the class! Even stranger was that he only wrote down one word!
What did he write?

10+10 and 11+11 can give you the same answer.

Explain how?

What has a ring but no finger?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??