Magic Cards




Introduction: Magic Cards

About: I'm a Mechanical Engineer and an enthusiastic Maker. I like to create and code my projects using the Arduino.

Hello, all !!

Today I will share you an amazing math game on its original version that my father has introduced to me when I was a kid.

Based on that, I have designed a new improved version but with the same kind of magic from the original one that I will introduce to you in my Instructable Magic Number.

It is a interesting game and it is also good for the kids increase their capability to sum numbers.

I offer this project to everyone and in special to the memory of my father, Marcos !!

Enjoy it !

Best regards,


Step 1: The Puzzle

  • Puzzle
  1. There are 06 cards with numbers from 1 to 63.
  2. Some numbers are printed in red color and another in black color.
  3. The person choses one of those numbers without telling it for anyone.
  4. Then he selects all the cards where they are in red color.
  5. Finally you see these cards, wait for some seconds and reveals to everyone the mysterious number chosen in the cards !
  • Material
  1. Print the template of cards.
  2. Cut all the cards.
  3. Play the game !
  • Solution
  1. Sum the first number in red color of all selected cards
  2. The result is the chosen number !!
  3. Piece of cake !
  • Example
  1. Imagine that the chosen number is 20.
  2. Select all cards that have the number 20 in red color.
  3. In this case, the cards #3 and #5.
  4. The first number shown in red on card #3 is 4.
  5. The first number shown in red on card #5 is 16.
  6. Adding (4 + 16) you have 20 !!!
  • The trick

    Binary numbers !!

    Note that each card have the numbers shown in red color according with a power of 2.

    We use decimal numbers (power of 10) for everything but computers, for examples, use binary numbers (power of 2) because you have only two numbers (1 or 0) that is the same of ON/OFF or TRUE/FALSE.

    That is the base of all electronic digital logics.

    Let's see an example to understand the conversion of bases between decimal and binary:

    Number 12 = 1 x (10 ^1) + 2 x (10 ^0)

    Binary of 12 = 1100 = 1 x (2 ^3) + 1 x (2 ^2) + 0 x (2 ^1) + 0 x (2 ^0) = 8 + 4 + 0 + 0

    So the cards are arranged to show only the numbers corresponding of each power of 2.

    That is the reason why you add all the first numbers of the cards where the chosen number is shown !!

    • Conclusion

    I hope you have fun with your kids, friends, family or school mate.

    If you practice a lot, you can calculate mentally the result just knowing the numbers of the cards of chosen number.



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