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This article was co-authored by Kevin Wang. Kevin Wang is a Math Tutor based in New York, New York. Kevin has been tutoring math for over 10 years, and specializes in K-12 math topics and standardized tests, such as SAT and ACT. Kevin has an economics background and a career in both finance and marketing analytics. His interest in tutoring goes back even longer than his career. He discovered tutoring at the start of his university career and enjoys it as a way to stay sharp with fundamental skills and remain up to date with trends in our education system. Kevin received a BS in Economics from Duke University.
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Mathematical mind reading tricks are a great way to combine your mastery of math with a bit of magical fun.
Steps
You ask the spectator to pick a number from 0 to 9 in his/her head. Later on after some steps they pick another number from 0 to 9. After one more step they tell you the answer and you can tell them the two numbers they picked in the same order!
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![Step 1 Ask them to pick a number in their mind from 0 to 9.]()
Ask them to pick a number in their mind from 0 to 9. ( Let's say 2 ). -
![Step 2 Tell them to double the number.]()
Tell them to double the number. ( 2+2=4 ).Advertisement -
![Step 3 Tell them to add five to the new number.]()
Tell them to add five to the new number. ( 4+5=9 ). -
![Step 4 Tell them to multiply the answer by five.]()
Tell them to multiply the answer by five. ( 9*5=45 ). -
![Step 5 Now tell them to remember the answer.]()
Now tell them to remember the answer. ( 45 ). -
![Step 6 Ask them to pick another number from 0 to 9.]()
Ask them to pick another number from 0 to 9. ( in this case 4 ) -
![Step 7 Ask them to add this number to their answer.]()
Ask them to add this number to their answer. ( 45+4=49 ). -
![Step 8 Ask them to tell you the answer.]()
Ask them to tell you the answer. ( 49 ). -
![Step 9 Listen to it carefully and then in your mind subtract 25 from the total.]()
Listen to it carefully and then in your mind subtract 25 from the total. ( 49-25=24 ) -
![Step 10 The first digit...]()
The first digit of the answer YOU get in your mind after subtracting 25 ( 24 ) is the first number they picked ( 2 ) and the second digit is the second number they picked ( 4 ).
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![Step 1 Understand the math behind this trick.]()
Understand the math behind this trick. Clearly no matter what you start with, the answer should come out the same (zero isn't allowed). You can see why this trick works by using a little bit of high school algebra; if you follow the instructions starting with the variable X instead of an actual number, you will see that X is eliminated by adding the example's number 17 (see below). -
![Step 2 Ham this trick up with magician's patter.]()
Ham this trick up with magician's patter.- The "original number" could be anything you want---someone's age, or their favorite number--- just ask the crowd for suggestions. This will change the final outcome, so test beforehand.
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![Step 3 Perform the trick:]()
Perform the trick:- Think of a number, any positive integer. Keep it small so you can do computations in your head.
- Square it.
- Add the result to your original number.
- Divide by your original number.
- Add, oh, how about 17.
- Subtract your original number.
- Divide by 6.
- The number you are thinking of now is 3!
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![Step 4 Make your own magic number trick.]()
Make your own magic number trick. Using this idea, you can make up your own mental math trick right on the spot. Just don't do anything too obvious, such as telling people to add 5, subtract their original number, and say "the number you are thinking of is 5".
Community Q&A
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QuestionWill this blow my friend's mind?
Community AnswerIt depends on which type of friend you have. If they are good at math, then you are at hard luck. If not, then this should surely surprise them. -
QuestionHow do I choose a number from 0-9?
Community AnswerRandom number generator. Just go to Google, search random number generator, add the limits from 0 to 9, and then voila! -
QuestionFor the second one, must you always divide by six?
Community AnswerYes, if you don't divide by 6, the answer will not always come out to 3.
Tips
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It is important to tell them to pick a number between 0 and 9 ONLY.Thanks
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Here's the math behind this mind trick: the person picks a number X, then multiplies it by two and adds five. You get 2X+5. You then multiply the result by five, you get: 10X+25. Te person picks a new number Y and adds it to the result, you get: 10X+Y+25. When you secretly subtract 25, you're left with 10X+Y, in other words a number whose tens digit is X and the units digit is Y.Thanks
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If the answer you get after subtracting 25 is 1 then the first number they picked was 0 and the second number they picked was one.Thanks
Warnings
- Don't tell anyone your secret, or everyone will know and it won't work any more.Thanks
Things You'll Need
- Someone to try it out with.
- Quick and accurate ways to get the answer in your mind.
About This Article
Cool mathematical mind reading tricks are a great way to entertain your friends. Ask someone to think of a number between 0 and 9. Then, tell them to double the number and add 5 to the new number. Using the new number, have them multiply it by 5. Now have them think of another number between 0 and 9 to add to their current number. At this point, have them tell you the answer. Once you know their final number, subtract 25 from it. The first digit of the answer you get is the first number they picked and the second digit is the second number they picked. To learn how to perform a more advanced mind-reading number trick, keep reading!
Reader Success Stories
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