Explain how this works

OK, so someone sent me an email with this site

Milaa Design

Please, can anyone tell me how it works?

I've done it 5 times, and 5 times its picked the right number.

I found this....


It's a multiple of 9 thing.

Pick a number represented by AB.
AB = 10A+B

Add the digits together (A+B)

Subtract that from the original number

AB-(A+B) = 10A+B-(A+B) = 10A+B-A-B = 9A

So, regardless of what number you pick, the result is 9 times the first digit of the number.

yes thats right, its a multiples of 9 trick
all the symbols are the same for multiples of 9

good stuff

it's a simple mathematics thing. the two numbers added together will always be the multiple of 9 below that set of tens. so take 43 for example. 4+3=7 43-7=36. now try 49. 4+9=13 49-13=36. they think they're really clever.

Theres a couple of other names for that trick but I could'nt find them, or remember.

But it threw me for a second when I first stumbled across it.

Symbol between 10 and 19 is same, result = 9
Symbol between 20 and 29 is same, result = 18
Symbol between 30 and 39 is same, result = 27
Symbol between 40 and 49 is same, result = 36
Symbol between 50 and 59 is same, result = 45
Symbol between 60 and 69 is same, result = 54
Symbol between 70 and 79 is same, result = 63
Symbol between 80 and 89 is same, result = 72
Symbol between 90 and 99 is same, result = 81

Or the multiples of 9.

m* (10) + n - m - n = 9 * m with m and n integers between 1 and 9. You will notice that the symbols of the multiples of 9 are each time the same, although each session a different symbol. That's the "trick".

Damn I need to type faster.