Chapter 4: Algebra... Reading Your Mind

Dear S1-02
Let's see who's able to unveil the mystery behind FIDO's magical mindpower!
Guess what!? I could read your mind too!
Guess How I Do It!

Explain how FIDO uses Algebra to read your mind :)
Click at Comments to enter your explanation...


  1. The person is able to guess the digit we select as the sum of the answer is always nine. If I choose 123 and then jumble the digits,I would get 321. As instructed in the game I would then subtract 123 from 321.
    321-123=198.The sum of the digits in 198 is 1+9+8=18 and the sum of digits in 18 is 1+8=9. If I circle 1 and type in 89 or 98, The sum of the digits is 9+8=17 and the sum of digits in 17 is 1+7=8. So to get the digit I would subtract 9-8=1. We subtract 8 from 9 because 9 is the sum of the answer. This would be the same formula to find out a chosen digit from a 4-digit number.

  2. i still don't understand
    can it even load?
    i mean the maths website (i think it gets stuck)

  3. I dont get the process, im not that sure about it either.

  4. This comment has been removed by the author.

  5. Even though Akhila's working is there, I still don't understand