TED-Ed: This one weird trick will get you infinite gold | Dan Finkel

A king demands his treasury's gold be tripled, and a magical man helps by using a special bag. The man later returns to claim a promised child, but offers a chance to guess his name. The bag's magic is explained as a function, and a riddle involving the number of coins is solved using logical reasoning.

What was the king's demand that led to the use of the magical bag?

• To halve the gold coins in his treasury

• To quadruple the gold coins in his treasury

• To triple the gold coins in his treasury

• To double the gold coins in his treasury

What did the protagonist promise the mysterious man in exchange for his help?

• A piece of land

• A royal title

• Their firstborn child

• A bag of gold coins

What condition did the mysterious man set to spare the protagonist's child?

• Find a hidden treasure

• Solve a math problem

• Complete a quest

• Guess his name

How does the magical bag function according to the mysterious man?

• It doubles the coins each time

• It triples the coins after two uses

• It adds five coins each time

• It subtracts coins randomly

How many coins did the protagonist deduce were in the man's hand?

• 19

• 20

• 22

• 23