What is the fastest way to double your money?

Imagine you are in a room with no windows or doors. How will you get out?

A wooden log balances equally on the scales when weighed with three-quarters of a pound and three-quarters of a wooden log.

Can you calculate the weight of the entire wooden log?

Birbal was jester, counsellor, and fool to the great Moghul emperor, Akbar.
The villagers loved to talk of Birbal's wisdom and cleverness,
and the emperor loved to try to outsmart him.
One day Akbar (emperor) drew a line across the floor.
"Birbal," he ordered, "you must make this line shorter, but you cannot erase any bit of it."
Everyone present thought the emperor had finally outsmarted Birbal.
It was clearly an impossible task.
Yet within moments the emperor and everyone else present had to agree that Birbal had made the line shorter without erasing any of it.
How could this be?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

Can you solve the below algebraic mathematical equation?

(J+O+I+N+T)3 = JOINT

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?

Why is a river so rich ?