A seven-year-old kid challenged his classmates that he can make the number one disappear by adding something to it.

How can he do that?

What goes up but never comes down?

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

You can see three almost identical images below. Can you spot the odd one out from them?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person's left hand? (For the purposes of this exercise, thumbs count as fingers, for five fingers per hand.) If you cannot estimate the number then try to guess how long the number would be.

Find The Next Number in the series:

12 13 15 17 111 113 117 119 123 ?

What part of the chicken has the most feathers?

A man wants to cross the pit of fire which is 25 feet in length and he has 2 planks(fire resistant) 19 feet in length. How can he cross the pit of fire alive?

I am lying and I always lie. Tell me whether I am lying or telling the truth.