It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

How many people must be gathered together in a room, before you can be certain that there is a greater than 50/50 chance that at least two of them have the same birthday?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

Take away the whole and some still remain. What is it?

Below the four parts have been reorganised. The four partitions are exactly the same in both arrangements. Why is there a hole?

There are three boxes. One is labeled "APPLES" another is labeled "ORANGES". The last one is labeled "APPLES AND ORANGES". You know that each is labeled incorrectly. You may ask me to pick one fruit from one box which you choose.

How can you label the boxes correctly?

You want to boil a two-minute egg. If you only have a three-minute timer (hourglass), a four-minute timer and a five-minute timer, how can you boil the egg for only two minutes?

In the given figure, move three matchsticks so that the resulting figure contains two rectangles.

I have a head like a cat and feet like a cat, but I am not a cat. What am I?