How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

A King wants to send the diamond ring to his girlfriend securely. He got multiple locks and their corresponding keys. His girlfriend does not have any keys to these locks and if he sends the key without a lock, the key can be copied in the way. How can King send the ring to his girlfriend securely?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

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

You are in a room with no metal objects except for two iron rods. Only one of them is a magnet.
How can you identify which one is a magnet?

Why do people go to bed?

Your last good ping-pong ball fell into a narrow metal pipe embedded one foot deep in concrete.
How can you get it out undamaged, if all the tools you have are your tennis paddle, shoe laces, and plastic water bottle, which does not fit into the pipe?

In a Society, there are over 100 flats.

Flat 1 is named the first flat.
Flat 2 is named the second flat.
Flat 3 is named the third flat. And So On.....

A visitor decides to walk through all the flats, and he finds all the flats except flat 62.
Anmol later founds that the locals of the town have given it another name.

What is the name of the Flat?

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

I am Huge on Sunday and Saturday.
I am small from Tuesday to Thursday.
I do not exist on Monday and Friday.
Who am I?