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Can you solve the counterfeit coin riddle? - Jennifer Lu

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3,601 Questions Answered

TEDEd Animation

Let’s Begin…

You’re the realm’s greatest mathematician, but ever since you criticized the Emperor’s tax laws, you’ve been locked in the dungeon. Luckily for you, one of the Emperor’s governors has been convicted of paying his taxes with a counterfeit coin, which has made its way into the treasury. Can you earn your freedom by finding the fake? Jennifer Lu shows how.

If you don’t know whether the counterfeit coin is heavier or lighter, what is the maximum number of coins for which three weighs are guaranteed to uncover the single counterfeit coin AND determine its relative weight?

About TED-Ed Animations

TED-Ed Animations feature the words and ideas of educators brought to life by professional animators. Are you an educator or animator interested in creating a TED-Ed Animation? Nominate yourself here »

Meet The Creators

  • Educator Jennifer Lu
  • Director Outis
  • Script Editor Alex Gendler
  • Associate Producer Jessica Ruby
  • Content Producer Gerta Xhelo
  • Editorial Producer Alex Rosenthal
  • Narrator Addison Anderson

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