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

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

Which statement is true out of the following?
One statement here is false.
Two statements here are false.
Three statements here are false.

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

I ask Joseph to pick any 5 cards out of a deck with no Jokers.

He can inspect then shuffle the deck before picking any five cards. He picks out 5 cards then hands them to me (Jack can't see any of this). I look at the cards and I pick 1 card out and give it back to Joseph. I then arrange the other four cards in a special way, and give those 4 cards all face down, and in a neat pile, to Jack.

Jack looks at the 4 cards i gave him, and says out loud which card Joseph is holding (suit and number). How?

The solution uses pure logic, not sleight of hand. All Jack needs to know is the order of the cards and what is on their face, nothing more.

Name a key which is hardest to turn.

How much will a 38° angle measure when looked at under a microscope that magnifies ten times?

Find the number of squares in the below-given picture.

While preparing the table for dinner, wife came up with an idea to tease his mathematician husband. She asked her husband to pick nine toothpicks and make ten without breaking any toothpick.

The husband was also smart and did it within seconds. How ?

Intelligence Agency need to break the vault but the problem is that they are not able to break the vault.

On the vault, a text is written as:

31 11 33 33 43 45
21 25
31 24 11 31 51 41

To Break the code Intelligence Agency brings a mathematician named Joseph.
Minutes later he deciphers the code.

Whats the code?