This simple math trick uses the binary number system. Don't worry, I'm not going to get into what a binary number system is and you certainly don't need to know it to dazzle your students with this trick. However, if you're curious, you should look it up--it's very cool!
Anyway, this is how it works:
- MS. MAI: Johnny, I can read your brain! Pick a secret number from 1 to 63. DO NOT tell me what it is. Then, write it on this little whiteboard without letting me see it. (This ensures that the student won't change his answer.)
- JOHNNY: Okay. (writes down the number)
- MS. MAI: Now, look at these 6 cards. Give me every card that has your secret number on it. If the card does not have your secret number on it, I do not want it.
- JOHNNY: Here you go Ms. Mai. Each of these cards have my secret number on it.
- MS. MAI: Hmmmmm...I'm reading your brain...(add the first number in the upper left-hand corner on each card: 2 + 4 + 16 = 22). Your secret number is...22!
- JOHNNY: (shows the number 22, written on his board to the class) How did you do that??
- MS. MAI: Magic.
I hope you enjoy this freebie! Thanks for hosting "Freebie Friday" Teaching Blog Addict!