Mystical ball

--- NATS wrote:

> try this magic:
>
> http://www.mysticalball.com/

THIS IS NOT MAGIC. of course!

any two digit number can be written as

a = 10*n + m

where n and m are any two numbers from 0 to 9

the first step involves taking the sum of n and m

first number = n + m = b

the second step involves subtracting b from a

second number = a - b
= (10*n + m) - (n + m)
= 9*n

which means that no matter what two-digit number you chose, you will always get a number which is a multiple of 9 since n=0,1,2,...,9

so the only possible final numbers are
9*0 = 0
9*1 = 9
9*2 = 18
9*3 = 27
...
9*9 = 81

now, look at the symbols for these numbers and you will see what i mean

that's the power of algebra!