This is cool to impress someone with your “paranormal” skills.

Put someone to choose a random number, preferably a large one ( 3 or 4 figures ), and he (or she) have to keep this number secret from you and do the following math with it:

xyz = he’s or she’s chosen number ( ex. 315 )

Step1: xyz * 3 ( multiply by 3, ex. 315 * 3 = 945 )

Step2: then take the result and add all it’s figures ( abcd => a+b+c+d , ex. 945 => 9 + 4 + 5 = 18 )

Step3: Repeat Step1 with the new number ( the sum of figures, ex. 18 * 3 = 54 )

Step4: Repeat Step2 ( ex. 5 + 4 = 9 )
…
Repeat steps 1 and 2 until you get a one figure number.

When the person or persons finished the above algorithm, you tell them the number they’ve got ( which with the algorithm above will be always 9 !), and the question that will appear will sure be “How did you know ?”, … :) try it!