Thursday, January 27, 2011

Can You Figure Out This Math Magic Trick?

A former boss of mine used to love astounding our students with this seemingly simple math magic trick.  First, he'd have you pick a number from 1 to 63.  He would show you each card, asking you if your number appeared on that card.  After showing you all six cards, he was always able to pinpoint your number within seconds.

I like to think I'm pretty good at math puzzles and tricks, but I couldn't figure this one out until he explained it to me.  Can you figure out the trick?

8 comments:

CLane said...

After they hand you the cards that do have the numbers, you add find the sum of the numbers in the upper left corner of each card.

New York Film Academy said...

neat thanks for the post

Cameron said...

its binary of course

Becky said...

I am always looking to trick my kids but I don't understand it. Please Help!

Noah said...

I am not really good when it comes to Math subject but I want to learn this kind of trick. It seems exciting:)

Mr. D said...

CLane's explanation is correct, but I wouldn't actually hand the cards to the person. It's much more impressive if you just flip through them quickly asking, "Is your number on this card?"

For example, let's say your number is 3. The number 3 only appears on two cards: one with 1 in the upper left corner and one with 2 in the upper left corner. Add them up and you've got your number. Try it!

Have fun using it! Once I learned the trick, I used to tell students that I could read their mind and prove it! :)

Adam said...

I've done this one with my 7th graders before... They are always amazed to see it work. I then take it one step further and have them try to figure out how the cards would change / what numbers would appear on each card if there were seven cards or if there where eight cards. All seem to find the experience enjoyable!

Anonymous said...

Excellent