Magic Numbers

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AMAZE YOUR STUDENTS WITH THIS MATH MAGIC TRICK!

Posted by Brittney Field on Aug 27, 2015

Want to show off a little ‘magic’ in math class tomorrow?  Want to watch your students’ jaws drop when they see you guess their secret number correctly again and again?  Let me teach you how to do the coolest (and simplest) math trick around!

I think you’re really going to love this one.  It’s easy to prepare and so much fun to do, even as adults.  Here’s how it works:

1. Click here to download a free PDF of the Magic Math cards. Print out the Magic Math cards page and cut out each of the cards individually.

2. Place all 6 cards face-up in a pile and put the “Pick a Number Between 1 and 30” card on top.  The order of the other 5 number cards does not matter.

3. Show your student the “Pick a Number Between 1 and 30” card and ask him/her to pick a number between 1 and 30.  Be sure that the student does not tell you what it is.

4. Show the student the first number card in the pile and ask, “Is your number on this card?”  Be sure that the student looks carefully before responding.

• If the student says “yes,” make a mental note of the number in the top lefthand corner of that card (it’s either 1, 2, 4, 8, or 16).
• If the student says “no,” just continue.

5. Show the student the next number card in the pile and do the same as you did before.

6. Repeat until you have asked the student for all 5 number cards.

7. You should have kept a mental note of the top lefthand corner numbers for all of the cards to which the student responded “yes.”  Add those numbers together.

• TIP: Keep a running total in your head as you move through the cards instead of waiting until the end to add them.  It’s much easier to remember a running total than to remember a bunch of different numbers.

8. The sum that you just calculated is the student’s secret number!  Now’s the fun part – blow the student away by sharing what his/her secret number is!

How cool and simple is that trick?  You can repeat it with your students again and again, but I guarantee that they will quickly want to learn how to do it themselves…

Dominoes

IN pairs, students grab 10 dominoes and put them face down. As quickly as possible (timed by partner) student turns each domino over and adds the numbers shown. Can be used for subtraction or multiplication also.