What brings you down but never up?

Two prisoners Jack and Jill are locked in a cell.
There is open window approx 40 feet above the ground of the cell.
They are never able to reach there.

Then they plan to escape by a tunnel and they start digging out.
After digging for more than 20 days, Jill comes with the different plan and they escaped.

what was the plan ?

I look at you, you look at me I raise my right, you raise your left. What am I?

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

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 time is it when an elephant sits on a fence?

What's a single-digit number with no value?

Can you tell a 3D object that has just two surfaces?

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?

Consider this about a word: The first two letters signify a male, the first three letters signify a female, the first four letters signify a great, while the entire world signifies a great woman. What is the word?