Only worked twice out of 15 tries.
just curious what numbers did you start with?
I made it simple like 65 -5 = 60
Wrong sign evertime
It would actually be 65 - 11 = 54
simple version would be 60-6=54, or 50-5=45 and so on...
Your answer will always be the first digit (of your two digit number) times 9
The same symbol appears by all the multiples of 9 up to 81, because you can't get 90 or 99 as your final answer...
still a pretty cool little trick...