Can you fill the blank with the correct number?

6 30 870 756030 _____

Once upon a time, there was a castle on a square island. The entire island was surrounded by a 14m wide trench. The Romans had wanted to invade the castle and had brought a few wooden planks along with them to facilitate themselves in crossing the moat. The planks were however found to be only 13m long.

The Romans still managed to cross the trench. How did they do it?

Decode below three cipher riddles:

26 L of the A
7 D of the W
1000 Y in a M

What does an Island and the letter T have in common?

What is the next number in this matchsticks series riddle?

It is a 5 letter word if you take away first letter it is something you get from sun, if you remove second letter you will get something to eat, if you remove third letter you get a word you use in pointing at and if you remove the fourth letter you get something to drink. What is it?

I was born in a small house and I live in it all alone. No windows and no doors have been assigned to my house. The only way I can go out is by breaking through the walls of my house.

Who am I?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

What word begins and ends with an E, but has only one letter?

How many minutes are there in Feb 2017?

Note: The shortest answer is the correct answer.