Wrote a short program to tell me the distance between hole centers for my Ti-86. It is the only thing I can write programs for. And even then it is input this, that, and the other, add this to that, and multiply by the other.
:Disp "Switch hole size"
:Input A
:Disp "Pitch"
:Input B
:Disp "1st key"
:Input C
:Disp "2nd key"
Input D
:((B*C-A)+(B*D-A))/2+A→E
:Disp E