Name a key which is hardest to turn.

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?

Why is the Hole below a Lock?

Consider all the numbers between 1 and 1 million. Among all these numbers, there is something very special about the number 8 and the number 2202. What is it?

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?

What has lots of eyes, but can’t see?

If your uncle’s sister is not your aunt, what relation is she to you?

Can you find out a way through which you can make five squares out of the given figure by moving just six match sticks?

Find out which of the given views in the picture is accurately the top view of the given pyramid.

What does does this rebus picture means ?