Sales Tricks: People Prefer Larger Denominations of the Same Thing (arstechnica.com)

Finally! A justification for charging in picodollars.

I thought this was a pretty well-known phenomenon. When comparing things, I always convert the numbers into the same scale... For most things, I pick a scale I'm comfortable with and convert to that. Months is a good one for long time ranges and work for converting everything from days to years. Pounds for weight, yards (or meters, really) for short distances, miles for long.

And if the things you're comparing are so far different that you can't fit both on the larger scale, do you really need to compare them?