Math Mind Reading Trick: The Answer is 3!

If you look over the internet, there you can find so many mind reading tricks. In this post, we are going to learn our first mind reading trick. This mind reading trick is easy to learn because it uses only numbers 1 – 10 and it has very few steps. It can be used by kids and youngsters.

The 3 Math Mind Reading Trick

Try doing the trick first and see if it works.

1.) Let your friend choose a number between 1-10.

2.) Tell him to multiply it by 2.

3.) Tell him to multiply the answer by 5.

4.) Tell him to divide the product by the original number (the one he chose in Step 1) and remember the quotient.

5.) Tell him to subtract 7 from the quotient. 

If your friend did the calculation correctly, the answer should be 3.

And example of this algorithm is shown below when the number chosen is 8.

math mind reading

The Secret Behind the Mind Reading Trick

The secret behind the mind reading trick is simple algebra. Suppose you choose any number n. In step 2, you multiplied n by 2, so you have 2n. In step 3, you multiply the answer in 2 by 5, you the answer is 10n. In step 4, we divide 10n by the original number which is n. Therefore, the answer in step 4 will always be 10. In step 5, we subtract 7 from 10, so the answer is 3.

If we write the expression above algebraically and simplify it, we have

\displaystyle \frac{n \times 2 \times 5}{n} - 7

= \displaystyle \frac{10n}{n} - 7

= 10 - 7

= 3

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One thought on “Math Mind Reading Trick: The Answer is 3!

  1. Pingback: Mind Reading Trick 2: The Answer is 4 - Math Tricks for Kids

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