Can you replace the question mark with the correct number?

Prove that twice of ten is the same as twice of eleven.

what does this picture(rebus) riddle means ?

No one wants to have it, but if one got it, he does not want to lose it. What is It?

Why do you find that most of the buildings are deprived of the 13th floor?

Can you spot the hidden girl in the picture below?

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 ?

Can you find the odd number in the following?

2716, 4135, 5321 and 7145

See the given image carefully. What you have to do is move the blue checkers in the position of the black checkers and vice versa. You are only allowed to move the checker to an adjacent empty space. Do it in the least possible moves.

A kind heart person buy packed food at 3$/packet from United states and sells them at 1$/packet at Africa. After some time he becomes a millionaire.

How come the guy become millionaire ?