Currently, the division symbol is used to represent fractional numbers. I would like to suggest the use of FRACTION SLASH (U+2044) instead. I think that would look better, and more intuitive.
Note that this symbol is different from a regular slash, /, in several ways. First and foremost, it has a different angle (usually closer to 45°). Secondly, its purpose is to render fractions, and some fonts take advantage of this and will render the numbers around the symbol differently (offset to to bottom left and top right respectively). Here's an example, and I'm not doing any tricks at all with the text, all I do it's to put the fraction slash in there instead of the division sign: 1⁄3456.
At least in Gmail on my phone thus renders beautifully. And even if the font doesn't have direct support for fractional rendering, it will still look nice.
Regards,
Elias