Saturday, 22 February 2014

6 AM Quiz: Let's Test FIDO out!

In this round of 6 am quiz, you will attempt to uncover the mystery behind Fido's Mind-Reading ability.

Fido claims that he can read our mind.
Click at the following link to test him out!!! :

There are several ways to explain Fido's trick, using mathematical reasoning. 
Make an attempt to use ALGEBRA to explain the "trick"?

Enter your thinking (algorithm) in Comments.


  1. Okay....
    I chose 4615 and made another which is 5164.
    I subtracted both of them and out with 549.
    I circled 5 and wrote 94 on the screen.
    Surprisingly, Fido gave the missing digit, 5!!!

    Fido's point of view:
    Digit 4 and 9 is given.
    Let the missing digit be 'x'.
    Possible numeral patterns are...
    - 100x+40+9
    - 100x+90+4
    - 400+10x+9
    - 900+10x+4
    - 400+90+x
    - 900+40+x

    Fido knows that the answer is always divisible by 9.
    Fido chooses one possible pattern: 900+40+x
    Possible value of x is 1,2,3,4,5,6,7,8,9.
    941 divided by 9= NOPE
    942 divided by 9= NOPE
    943 divided by 9= NOPE
    944 divided by 9= NOPE
    945 divided by 9= YES!
    945 is divisible by 9.

    So the missing digit is 5!!!

    1. Phew...
      That was hard~
      Is it right, Ms Loh?

    2. @Gijoo
      Hope that you find this interesting and has challenged you to think deeper :)
      That's the 'magical' touch that algebra gives :)


    3. The answer is correct. Its very interesting and in depth. Good job Gijoo!