# Thread: Try this for fun

1. ## Try this for fun

Try this for the fun of it.

2. 18

3. Hrm...wait...no...

lost...

4. haha this game got me quite a while....finally got it...

5. noticed that the symbols accompanying the numbers keep changing. but still dont know why

6. Wahhhh!!!! So scary!!! How does it know??!!

7. what is the secret??

8. Keep it running for a few days, will reveal it later.

9. The answer will always be the symbol associated with the multiples of 9 (which are all the same symbols)!

10. Originally posted by SzennyBoy
The answer will always be the symbol associated with the multiples of 9 (which are all the same symbols)!

You know about it! I've just completed 9, 18, 27 only.

11. can some mathematician explain why a 2 digit number - the sum of the 2 digits will result in a number that is a multiple of 9. 10s.

12. figured it out liao, but only after i know the result ...

13. aaargh got this in a mail some time ago. but i figured out how it works. well heres the spoiler. according to the law of mathematics. its seems that any 2 digit numbered thats has its numebers added then subtracted from the orginal number will always be a multiple of 9. Sooooo if u notice all the multiples of 9 have the same symbol. so there u have it. No it cannot read our mind

14. OK. Here's some algebra:

For the 2-digit number that you pick, let "a" be the most significant digit and "b" be the least significant digit, thus 1<=a<=9 and 0<=b<=9.

"a" cannot be 0 or else it will not be a 2-digit number anymore.

Then the 2-digit number has a value of 10a + b
The sum of the 2 digits is a + b

Subtract the sum of the 2 digits from the original 2-digit number, and the result is (10a + b) - (a + b) = 9a.

Since "a" is an integer from 1 to 9, then the result is always a multiple of 9 (from 1x9=9 to 9x9=81), no matter which 2-digit number you pick at the beginning.

So, the trick is to assign the same symbol to all multiples of 9 from 9 to 81, and always show that symbol in the crystal ball. even though 90 and 99 are also multiples of 9, they will not be the results because the limit is 9x9 = 81. So the symbols for 90 and 99 can be different.

- Roy

15. roygoh, you sure knows your sums well.

16. Originally posted by roygoh
OK. Here's some algebra:

For the 2-digit number that you pick, let "a" be the most significant digit and "b" be the least significant digit, thus 1<=a<=9 and 0<=b<=9.

"a" cannot be 0 or else it will not be a 2-digit number anymore.

Then the 2-digit number has a value of 10a + b
The sum of the 2 digits is a + b

Subtract the sum of the 2 digits from the original 2-digit number, and the result is (10a + b) - (a + b) = 9a.

Since "a" is an integer from 1 to 9, then the result is always a multiple of 9 (from 1x9=9 to 9x9=81), no matter which 2-digit number you pick at the beginning.

So, the trick is to assign the same symbol to all multiples of 9 from 9 to 81, and always show that symbol in the crystal ball. even though 90 and 99 are also multiples of 9, they will not be the results because the limit is 9x9 = 81. So the symbols for 90 and 99 can be different.

- Roy
I go down on my knees and say:
"I'm not worthy! I'm not worthy!"

17. Originally posted by Goondu
roygoh, you sure knows your sums well.
Originally posted by Sin
I go down on my knees and say:
"I'm not worthy! I'm not worthy!"
paiseh...paiseh...

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