What is the centre of gravity?

I am a type of room you cannot enter or leave. Raised from the ground below, I could be poisonous or a delicious treat. What am I?

Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

The more of this there is, the less you see. What is it?

In the image below, you can see two glasses and two matchsticks.You need to move four matchsticks in such a manner that the crosses come inside the glasses. Note: you cannot move the crossed.

The person who makes it has no need for it; the person who buys it has no use for it. The person who uses it can neither see nor feel it. What is it?

When is the top of a mountain similar to a savings account?

There are three houses in a straight row. One is red, one is blue, and one is white. The red house is left of the middle. The blue house is right of the middle. Where's the white house?

Baseball bat and ball cost $100. If the bat cost $99 more than the ball, what is the cost of each?

How can you write nineteen in a manner that if we take out one, it becomes twenty?