Sunday, October 29, 2017

AMAZING MATH TRICKS

The 7 - 11 -13 trick!

This trick makes you look like your brain is a mega fast calculator! 

 Ask a friend to write down ANY three digit number such as 231 

    or 884. 

Ask them to multiply the number by 

x 7 

x 11

 x 13 

 ...but even if your friend has used a calculator, you will have 

    written down the answer ages ago! 

THE SECRET: all you do is write out the starting number 

    twice!

    So 231 will become 231231 and 884 will become 884884. 

You don't believe it? Well try it on this calculator and see for 

yourself! You work this calculator by clicking the mouse on the 

buttons. 

Go on, put in ANY three digit number then x 7 x 11 x 13 and see 

what you get!


The 3367 trick:


This trick is similar to the 7-11-13 trick. It's harder to do, but it 

looks far more miraculous! 

 Get a friend to pick any 2 digit number e.g. 74 

 x 3367

 To work out the final answer you have to imagine the original 

      number written out three times e.g. 747474 then divide it by

      three. 249158 

 This one takes practice, but unlike the others, it's very hard to see

     how it's done! 



THE MISSING DIGIT TRICK!

Here it is!

  Cover your eyes in some way so that you can't see what your 

      friend is writing. 

 Ask a friend to secretly write down ANY number (at least four 

    digits long). e.g. 78341 

 Ask the friend to add up the digits... e.g. 7+8+3+4+1 = 23

  ... and then subtract the answer from the first number. 

     e.g. 78341 - 23 = 78318 

 Your friend then crosses out ONE digit from the answer. (It can 

     be any digit except a zero) e.g. 7 x 318

  Your friend then reads out what digits are left .e.g. 7-3-1-8 

 Even though you haven't seen any numbers, you can say what 

     the missing digit is! EIGHT

  THE SECRET  

This great trick relies on the power of 9. 

 After your friend has added up the digits and subtracted them, 

     the answer will ALWAYS divide by 9. If a number divides by 

     nine, then when you add the digits up, they will also divide by 9.

     If you check our example 7+8+3+1+8 = 27 which does divide 

     by nine.

  When your friend crosses a digit out, he then reads out the 

      digits that are left. You add them up. In the example we had 

      7+3+1+8 = 19 

 All you do now is see what you have to add on to your answer 

     to get the next number that divides by nine! The next number to

     divide by 9 after 19 is 27. So you need to add on EIGHT. This 

     is the number that was crossed out!




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GOTTFRIED WILHELM LEIBNIZ THE FATHER OF CALCULUS 372 TH BIRTHDAY

https://en.wikipedia.org/wiki/Gottfried_Wilhelm_Leibniz https://www.youtube.com/watch?v=FPCzEP0oD7I