If eleven plus two equals one, what does nine plus five equal?

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

I am lying and I always lie. Tell me whether I am lying or telling the truth.

You see me once in June, twice in November, and not at all in May. What am I?

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.

Sahir enters the bank aims to rob and finds Jai standing inside armless. He aims a gun at him and asks him the code for the safe. Jai says, 'The code is different every day but if you hurt me, you will never get to know the code'.

Sahir pins him down and ties him with a rope. He then inserts the safe code and easily takes all the money with him.

How did he know the code?

What has 13 hearts but no other organs?

A time long back, there lived a king who ruled the great kingdom of Trojan House. As a part of the renovation of the kingdom to meet future security needs, he asked his chief architect to lay down a new play in a manner that all of his 10 castles are connected through five straight walls and each wall must connect four castles together. He also asked the architect that at least one of his castles should be protected with walls. The architect could not come up with any solution that served all of King's choices, but he suggested the best plan that you can see in the picture below. Can you find a better solution to serve the king's demand?

There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

Can you find the missing piece of the Porsche?