The one we could never solve was something like 7,7,8,9
If you were allowed to rearange the digits 7 + 8!/7! + 9 = 24. We played the same game on trains (our train carriages conveniently have 4 digits identifications) so we had some pretty messed up functions towards the end of highschool.
27 is 3^3
Kefka's coming, look intimidating!
Have a nice day!!