Can you solve the locker riddle?  Lisa Winer

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Your rich, eccentric uncle just passed away, and you and your 99 nasty
relatives have been invited to the reading of his will. He wanted to
leave all of his money to you, but he knew that if he did, your
relatives would pester you forever. Can you solve the riddle he left for
you and get the inheritance? Lisa Winer shows how.
About TEDEd Originals
TEDEd Original lessons feature the words and ideas of educators brought to life by professional animators. Are you an educator or animator interested in creating a TEDEd original? Nominate yourself here »
Meet The Creators
 Educator Lisa Winer
 Director Outis
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Additional Resources for you to Explore
The locker problem is often used as an introduction to factors, multiples, square numbers, prime numbers, and sequences. It shows that some problems can be solved using a smaller, simpler problem rather than brute force (also known as the method of exhaustion). Here is a more detailed video solution to the locker problem, and here is a related problem that uses Othello pieces instead of lockers.
If you enjoyed the locker problem, you might enjoy studying figurate numbers. Another fun problem to investigate is the handshake problem. An interesting extension is to write square numbers as the sum of odds. Visit the educator's blog that links these units together, and another that is from the viewpoint of students who learned about it.
Love riddles? TEDEd has plenty of them that will challenge you:
The famously difficult greeneyed logic puzzle  Alex Gendler
Can you solve the prisoner hat riddle?  Alex Gendler
Can you solve "Einstein’s Riddle"?  Dan Van der Vieren
Can you solve the temple riddle?  Dennis E. Shasha
Can you solve the frog riddle?  Derek Abbott
If you enjoyed the locker problem, you might enjoy studying figurate numbers. Another fun problem to investigate is the handshake problem. An interesting extension is to write square numbers as the sum of odds. Visit the educator's blog that links these units together, and another that is from the viewpoint of students who learned about it.
Love riddles? TEDEd has plenty of them that will challenge you:
The famously difficult greeneyed logic puzzle  Alex Gendler
Can you solve the prisoner hat riddle?  Alex Gendler
Can you solve "Einstein’s Riddle"?  Dan Van der Vieren
Can you solve the temple riddle?  Dennis E. Shasha
Can you solve the frog riddle?  Derek Abbott
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About TEDEd Originals
TEDEd Original lessons feature the words and ideas of educators brought to life by professional animators. Are you an educator or animator interested in creating a TEDEd original? Nominate yourself here »
Meet The Creators
 Educator Lisa Winer
 Director Outis