Weird

Weird

On a close inspection there are shapes that repeat.

When you do the math there is only something like 16 or so out of the 99 that you are able to actually get by doing this.

example:- 79-(7+9)=63), 80-(8+0)=72, 81-(8+1)=72, 82-(8+2)=72, 83-(8+3)=72, 84-(8+4)=72,  85-(8+5)=72, 86, 86-(8+6)=72, 87-(8+7)= 72,  88-(8+=72, 89-(8+9)=82, 90-(9+0)=81

So all they have to do is make sure that the possible options are the same shape every time, then the others can be completely random. (0, 9, 18, 27, 36, 45, 54, 63, 72, 81)