Can you find the odd number in the following?

2716, 4135, 5321 and 7145

I have Rs.50 and I spend it in the way as below.

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

A boy was locked in a room by some robbers. All that is in the room is a piano, a calendar, and a bed. The room is locked from the outside. What does he eat, drink, and how does he escape and get out?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

A man is found unconscious in front of a store at two in the morning. His head is bleeding and there’s a brick laying next to him. When the police arrive, they carry the man to jail. Why did they arrest him?

If I put in one bird per cage, I have one bird too many. If I put in two bird per cage, I have one cage too many. How many cages and birds do I have?

It begins where the time ends.
Its second is an expression of surprise.
Its third is a question.
Its fourth is urinate.
It ends with a drink.

Which country it is?

You have a 12 liters jug full of water. You have two empty 8 liters and 5 liters jug. How can you divide the water into two equal parts using these jugs?

A newspaper is supposed to have 60 pages, but pages 24 and 41 are missing.
Which other pages won't be there?