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

Prove that twice of ten is the same as twice of eleven.

There were three women in all the swimming costumes!
One was happy and the other two were sad!
The happy one was crying and the sad ones were smiling.
Why was this?

One absent-minded ancient philosopher forgot to wind up his only clock in the house. He had no radio, TV, telephone, internet, or any other means for telling time. So he travelled on foot to his friend's place a few miles down the straight desert road. He stayed at his friend's house for the night and when he came back home, he knew how to set his clock. How did he know?

There are 3 apples in the basket and you take away 2. How many apples do you have now?

John can place six large boxes or nine small boxes into a carton.

Can you find out in how many cartons can he place sixty-six boxes in total?

"That Restaurant always remains crowded. This is the reason why nobody goes there".

Can you find a flaw in this statement?

As a whole I am both
safe and secure.

Behead me and I become
a place of meeting.

Behead me again and I am
the partner of ready.

Restore me, and I become
the domain of beasts.

What am I?

The day before yesterday I was 25 and the next year I will be 28. This is true only one day in a year. What day is my birthday?

The horse jumps over the king.
Strangely there is absolutely no scratch on him.

Can anyone explain, how is this possible?