What is the largest amount of money that you can possess in change and still if someone asks you for a dollar, you won't be able to give?

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

What makes this number unique: 8,549,176,320?

It has horns but can’t beep. It is like to bleat but It is not a sheep. What is it?

For an extra income, John decided to work at a Hotel for one hour daily. The manager offers him that they will pay him $11 after every 11 days.
However, John offered a different proposition to the manager. The offers stand as:
He will be paid just a penny on his first day.
Two pence will be paid on the second day,
Four pence will be paid on the third day.
And so on till the 11th day.

Should the Hotel manager accept his offer?

A swan sits at the center of a perfectly circular lake. At an edge of the lake stands a ravenous monster waiting to devour the swan. The monster can not enter the water, but it will run around the circumference of the lake to try to catch the swan as soon as it reaches the shore. The monster moves at 4 times the speed of the swan, and it will always move in the direction along the shore that brings it closer to the swan the quickest. Both the swan and the the monster can change directions in an instant.
The swan knows that if it can reach the lake's shore without the monster right on top of it, it can instantly escape into the surrounding forest.

How can the swan successfully escape?

Find the next number in the series

12, 20, 40, 72, 116, 172 ?

Two girls were born to the same mother, on the same day, at the same time, in the same month and year and yet they're not twins. How can this be ?

If eleven plus two equals one, what does nine plus five equal?

Which alphabet is a part of our body?