Can you circle exactly four of these numbers such that the total is twelve?

1 6 1
6 1 6
1 6 1
6 1 6

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?

In case you were starting to feel confident, this one was meant for third graders in Vietnam. The answer is 66, but we don't blame you for scratching your head about how they got there.

A man in a car saw a Golden Door, Silver Door and a Bronze Door. What door did he open first?

Known by all without exception, Forever here, for your protection, Sometimes strong, sometimes weak, Right after the night I come - hot and chic. And while millions of miles away, I always get to you, I find my way. No life around could do without me, Can you guess what I might be?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

Which digit occurred maximum times between the number 1 and 1000?

Find the next number in the series.
1 10 24 43 67 ?

In this image, you can see three almost identical Doraemon images. Can you spot the odd one out from them?

I am white when I am dirty, and black when I am clean. What am I?