Can you convert the number zero(0) into a positive number using just one mathematical operator ?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

Below toothpicks/matchsticks indicate the group of fishes moving from west to east direction. Can you make them move from east to west by just moving three toothpicks/matchsticks?

What is the riddle which can be asked all day with a different correct answer each time.

A wealthy man lives alone in a small cottage. Being partially handicapped he had everything delivered to his cottage. The mailman was delivering a letter one Thursday when he noticed that the front door was ajar. Through the opening he could see the man's body lying in a pool of dried blood. When a police officer arrived he surveyed the scene. On the porch were two bottles of warm milk, Monday's newspaper, a catalog, flyers, and unopened mail. The police officer suspects it was foul play. Who does he suspect and why?

You are provided with a grid (as shown in the picture). Can you fill the squares with numbers 1-8 in a manner that none of the two consecutive numbers are placed next to each other in any direction (vertically, horizontally or diagonally?)

There are nine letters in the below-given diagram. You have to form a nine-letter word using these letters.

What begins with T, ends with T, and has T in it?

John is found dead in a bare field. Nobody killed John,
John did not commit suicide.

Inspector Jacob found a bag just a few meters away from John which could save his life. What was in the bag?

Place the numbers from 1 to 9 in the circles in a manner that each side of the triangle sums up to 17.