Situation :
Call your friends and tell them that you are able to read their mind. Ask them to think a number and don't let you know the number they are thinking. When they are counting you may act as a magician by closing your eyes and raising your hands to the sky.
Instruction :"Think a number and don't let me know the number. Multiply the number with three, added by four, multiplied by two, divided by 2, added by two, divided by three and the last is subtracted by the number in your mind"
They will be surprise after you tell them that the the number their thought is "two".
Secret :Whatever numbers they put in, the answer is always "two". Why? By using algebra equation!
If the number given is x, so we get the formula :
{[(2(3x+4)):2]+2}:3-x=2The way :
If you want the answer is "
three" just follow these steps:
(x+3)-x = 3and put times
2 (or whatever number you want to put in) :
(2(x+3):2)-x=3Expand the equation
(2x+6):2-x=3Change the equation to be
[(2x+4)+2]:2-x=3and put times
3 (or whatever number you want to put in) :
{[3(2x+4):3]+2}:2 - x = 3And the last, expand the equation :
{[(6x+12):3]+2}:2 - x = 3So, the instruction will be "Multiply the number you're thinking with 6, add 12, divided by 3, added by 2, divided by 2, and subtracted by the number"
And prove it if we put the number is 10 :
6 x 10 = 6060 + 12 = 7272 : 3 = 2424 + 2 = 2626 : 2 = 1313 - 10 = 3Have fun with math !!!
Due date : Monday, December 7, 2009
Materials: You may use dices, playing cards, dominoes, spinners, etc.
