what does the below math rebus puzzle mean?

What is the next number in this series?

4,12,84,3612....

It has a long neck, A name of a bird, Feeds on cargo of ships, It's not alive,

What is it?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.

John went to buy some expensive, foreign chocolates. He only had Rs 100 with him. When he reached the shop, he got out and know that on those chocolates, there was a 15% import duty and 5% VAT.

How much worth chocolate should he buy so that he can accommodate it in Rs 100?

What does Alexander the Great and Winnie the Pooh have in common?

What's the only room from which no one can enter or leave

Why is the Hole below a Lock?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?