I’m tall when I’m young, and I’m short when I’m old. What am I?

A train full of passengers goes through a tunnel. When the train comes out from the other end, there is no single person on the train.

How did it happen?

Cristina was born in 1888. She just had her 30th birthday today how did that happen?

There was a competition where the contestants had to hold something. At the end of the event, the winner was a person who had no hands or feet. What was it that the contestants had to hold?

I have two sand hourglasses:
1. A 7 minute one and
2. An 11-minute one.

Using just these 2 sand hourglasses, how can I measure time as 15 minutes?

Can you find the odd number in the following?

2716, 4135, 5321 and 7145

Replace the question mark with the correct number in below Picture:

Out of the nine cats that you can see in the picture, there are only two that are completely identical. Can you find them out?

Can you count the number of lines in the below picture?

You have $100 with you and you have to buy 100 balls with it. 100 is the exact figure and you can't go below or above the numbers and you have to use the entire $100. If there is no kind of tax applied how many of each of the following balls will you be able to buy:

Green Balls costing $6
Yellow Balls costing $3
Black Balls costing $0.10

Now, how many of each must you buy to fulfil the condition given?