**Scientific notation would have you display this as: 1.23e5**, it's more 'correct' when it comes to units: 1.23e5 m is right, whereas 123k m isn't (it should be 123 km).

However if your users aren't comfortable with the 'k' postfix then I doubt they'd like this much, I merely mention it for completeness.

Other possibilities might be to have something like: **123<sup>thou</sup> or 123<sup>,000</sup>**