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

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

Christina, Allison and Lena are 3 daughters of John a well-known Mathematician, When I asked John the age of their daughters. He replied "The current age of her daughters is prime. Also, the difference between their ages is also prime."

How old are the daughters?

A frog is at the bottom of a 30-meter well. Each day he summons enough energy for one 3-meter leap up the well. Exhausted, he then hangs there for the rest of the day. At night, while he is asleep, he slips 2 meters backwards. How many days does it take him to escape from the well?

How much will a 38° angle measure when looked at under a microscope that magnifies ten times?

The measurement of time, That can't be found on a clock, But can be looked upon on a map.

Who is He ?

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.

A man was just doing his job when his suit was torn. Why did he die three minutes later?

What jumps when it walks and sits when it stands?