Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

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

See the given image carefully. What you have to do is move the blue checkers in the position of the black checkers and vice versa. You are only allowed to move the checker to an adjacent empty space. Do it in the least possible moves.

You are playing a game with your friend Jack. There are digits from 1 to 9. You both will take turn erasing one digit and adding it to your score. The first one to score 15 points will win the game.

Would you want to play first or second?

PS: The sum should be exactly 15.

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.

You’ll find me on Mercury, Earth, Mars, Jupiter, Saturn, and Uranus. But never Neptune, or Venus. What am I?

81 x 9 = 801. What must you do to make the this equation true?

In front of you, there are 9 coins. They all look absolutely identical, but one of the coins is fake. However, you know that the fake coin is lighter than the rest, and in front of you is a balance scale. What is the least number of weightings you can use to find the counterfeit coin?

What is the difference between a jeweller and a jailer?

What has no start, end, or centre?