There's a stack exchange comment saying it's harder to forge $20 to $320 than it is to forge 20$ to 320$.

http://english.stackexchange.com/questions/11326/what-is-the...

http://english.stackexchange.com/questions/34013/why-is-the-...

I'd like to know why we do it too. I mean, I know "just because" but I'd like to know how it started.

The decimal point protects the right edge of the amount, while the dollar sign protects the left edge.

Similarly, when people write out a number in English on a check, they often write "Twenty dollars only", not just "Twenty dollars", in order to prevent other words from being added to the end, e.g. "Twenty dollars and a hundred". (There's a nursery rhyme that goes "four and twenty blackbirds", so writing the smaller number first is clearly not unheard of.)

(Except in Belgium and Switzerland and this-one-valley-in-Italy et cetera, where it is just "nonante-trois".)

Compared to that, "drei-und-neunzig" is still not bad.

This is why you fill the empty part of the field with a long horizontal line.

Was this really a problem at some point? My friends have told me about it, but my parents never bothered to mention it to me growing up.

Luckily, though, it is common to use commas to separate groups of three digits: $200,000.00 But this means a change of a factor 1000 which might be less useful than the original 20$ -> 320$ example.

If I have a legal document where I need to be certain of its provenance after going out into the world, it is a digitally signed PDF.

If I print a paper check where the numbers need to be tamper-resistant against casual forging, I use a secure number font. I don't anticipate ever being in a position where my adversary in that use case is a determined, professional forger. I'd insist upon encrypted and/or insured electronic transactions, like through SWIFT or ACH, before I get to the point I'd be worried about professional forgers.

In Chinese, some characters representing numbers are so trivially forgible by adding a stroke or two (1 = 一, 2 = 二, 3 = 三, 10 = 十, 1000 = 千) that accountants came up with complicated substitutes that cannot be altered to mean any other number (1 = 壹, 2 = 贰, 3 = 叁, 10 = 拾, 1000 = 仟). The substitutes are still widely used in legal and financial documents.

eg http://www.independent.co.uk/news/business/news/facebooks-ma...

Years ago an acquaintance of mine told me about a bad experience he had had with some cell company's customer service. It seems that the contract he had received had said that he would be charged for data service at the rate of ".02¢/kilobyte". (This was in the very early days of cellular data, so prices weren't well established, and I'm probably not remembering the correct number, but as you'll see, that's not the point.) When the bill came, he found that he was in fact charged 2¢/kB -- 100 times more than he expected. He called to complain, but was unable to communicate to the customer service agent that, correctly read, .02¢ = $.0002. The agent apparently looked at the notation ".02¢" and read it as "$.02".

One can understand the psychology of this. The notation ".02¢" contains two indications that the value 2 is to be multiplied by 1/100: one is given by the position of the decimal point, and the other by the use of the cent sign instead of the dollar sign. But if you read those two indications as redundant rather than independent, you get the interpretation used by the agent (and apparently also by the person who wrote the contract).

So I would suggest that the "$10 dollars" thing is not as benign as it appears. Mathematical notation is not supposed to have redundancies in it, and we should not get used to seeing them there -- particularly when money is involved.

[1] http://verizonmath.blogspot.co.uk/2006/12/verizon-doesnt-kno...

Not quite the same thing, but I had a senile biology teacher who looked for any pretense to deduct points on papers. For example, when you reported data from lab work in tabular form: "points off -- these numbers don't have units". "But the column headings indicate the units -- that would make it redundant!" "Not good enough."

Malaysians write theirs like "RM8"; RM being their local currency symbol despite the ISO one being MYR (this happens because ISO puts the country first but many countries would write it out the other way around).

A bunch of other countries don't write any symbol at all, only the number. Some, like Indonesia, also have an implied thousands (000) at the end, since their base currency unit is very small. So you may see "8" but it means "8000 IDR."

one could argue that "10 USD" is even better overall, with the negative of requing two extra chars.

because I do take those situations into account. if it would cause a problem with others I don't do it. in my own notes or when dealing with others whose brains I know can handle it, I do.

[0] http://www.joeydevilla.com/2008/08/13/countries-that-dont-us...

That'll teach me, I guess, for taking photos near Area 51 :)

I guess its fruitless to try and apply logic to language and better to just accept the general usage?

On the other hand, it's also worth noticing that scientific units come from science, but monetary units come from finance. The regularised SI system is only a couple of hundred years old, and ledger entries are much older. My guess is that merchants in ye olde Europe had to deal with a variety of currencies, and putting the currency first was convention. It may have also made it clearer in a manifest as to which column was cost and which was amount, in an era when weights and measures were highly varied. Absolutely no supporting data for this, just a hunch :)

When suffexed, i mostly see "EUR" or "EURO" used instead of the € symbol: 123,40 EUR.

Your experience is a minority, and most likely sourced in a country which doesn't use the Euro as its currency (like the UK)

By and large, European locales (this is orthogonal to language) put the € sign at the same place they put their previous currency signs, and for most of them it's after: the Dutch, Austrians, Cypriots, Irish, Liechtensteiner, Latvian and Maletese use the prefix form, everybody else uses postfix (about 80% of EU population, slightly more than that wrt Euro-using countries as the UK amounts for 12.5% of the EU population but doesn't use the Euro)

See http://en.wikipedia.org/wiki/Linguistic_issues_concerning_th... for a reasonably complete table.

Colloquially, EUR values are expressed with the currency symbol following the value, but in nearly all business correspondence (i.e. invoices, contracts, etc), it is actually prefixed and in many cases (likely for historical compatibility reasons) spelled out.

In other words, in day-to-day use you'd likely see this:

123,40 €

In more formal situations and invoices you'd expect this:

EUR 123,40

I'm not sure whether this split pre-dates the Euro. I recall seeing "DM 123,40" before the Euro, but I was too young to pay much attention to that kind of thing. Most signage used "123,40 DM" or even "12 Pf." (for Pfennig, the equivalent of cents) or left it off entirely, I think.

I wonder if $20 comes from the appropriate order for Spanish, now that I know the $ symbol comes from Spanish!

  | sacks of barley          |    130 |
  | kegs of wine             |     12 |
  | pesos de ocha            |  2,800 |

But in about any language the currency symbol comes before the number.

It'd be just as appropriate if Anno Domini was translated into English.