Adni, come one. Look at the chart.
Well, David didn't want me to spoil it, but I will.
So:
DISCLAIMER: I WILL SPOIL THE TRICK
Adni, ANY two digits number, when you add both digits together and substract the total from the original number will ALWAYS give you a multiple of 9. You know what a multiple of 9 is, right? It's a number that is divisible by 9, such as 9, 18, 27, 36, 45, 54, 63, 72, 81, 90, etc. Try it, you'll see:
76? 76-(7+6)=63 (multiple of 9)
92? 92-(9+2)=81 (multiple of 9)
12? 12-(1+2)=9 (multiple of 9)
30? 30-(3+0)=27 (multiple of 9)
99? 99-(9+9)=81 (multiple of 9)
Try any number you want. It will always be a number divisable by 9.
Now look at the chart. All the multiples of 9 have the same symbol: 9, 18, 27, 36, 45, 54, 63, 72, 81.
Tadam!
