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Comment by btgeekboy | Hacker News Reader

The assumption that every possible value from 0 to 99 is equally likely doesn't seem like the best idea. In a country where the cost of items usually ends in .99, .97, or the like, and the sales tax is added after the fact (and usually from 0-10%), is it still the best choice? The post (and cited paper) don't seem to mention this.

That said, I don't know where you'd acquire these sorts of statistics.

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But taxes vary throughout the areas. And adding more items together. and splitting the dinner bill among friends. and all sort of other things that can make the final total anything from 0 to 99. I don't think it is silly to make the assumption they are equally likely. But I also don't know where you'd acquire these sorts of statistics.

Completely agree: prices are not set arbitrarily or via direct calculation in many cases, but are driven by marketing ($1.99) or optimization (the local pizza shop that works everything out to even $ or 50c).

I also wondered about the random assumption. The thing that made me question the assumption the most is Benford's law.

I don't think Benford's law applies here: it's about the first digit of numbers (that are distribute in a certain way), but in most cases the first digit of a price will be denominating dollars, not cents.

The leading digit of change is tens of cents...

The change may be more than a dollar, so tens of cents is not necessarily the leading digit.

the amount of coin change is never more than a dollar.

The amount of coin change is the remainder left over after dividing the total change by a dollar. Thus although the total change may or may not obey Benford's Law, the coin change certainly doesn't.

Credit card companies would know, but probably not publish.

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