Because that's still 2 numbers, complicating comparisons and arithmetic, and the more important number is at the end. If you could use e7.5 then that would all

Because that's still 2 numbers, complicating comparisons and arithmetic, and the more important number is at the end. If you could use e7.5 then that would alleviate the problems, but no software/language/calculator accepts this notation, and using a caret like ^7.5 is more evocative than the already very-overloaded "e".