Replace the question mark with the correct number in the below-given picture?

I am quite hot but become too cold if you remove the first two letters. What am I?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

What do you get if you add 2 to 100 four times?

John and Jill are madly in love with each other. To remind Jill of his pure love, John wants to send her a ring by post but in their country where burglary is quite prominent, any package that is not locked comes under the risk of being stolen for the contents.

John and Jill possess many padlocks but neither one of them has the other key.

Can you find a way John can send the ring to Jill safely?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

What demands an answer, but asks no questions

What am I?

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?

What building has the most stories?