How should references to amounts of money be styled? The key to answering that question is context.
Casual, isolated references, as well as approximations, are generally spelled out, as in the examples below:
“I’m just putting in my two cents’ worth.”
“Remember when a candy bar cost twenty-five cents?”
“I have only five dollars in my wallet.”
“She loaned him a thousand dollars.”
“I wouldn’t trade it for a million dollars.”
However, in financial contexts—those involving anything from numerous references to salaries of specific athletes in a book about professional sports to pervasive citations in a book about business or economics, use the dollar sign and numerals: “He was the first professional football player to earn an annual salary of more than $1 million.”
Note that for round figures, using a pertinent figure followed by a term for an order of magnitude (such as million) is preferable to numeric notation ($1,000,000), unless the figure is precise, as in “The charitable event raised $1,567,893.” Generally, however, such precision is unnecessary, and an amount can be expressed with rounded-up approximation: “The charitable event raised $1.6 million.” (A casual reference can read “1.6 million dollars.”) In some financial contexts, K is used as a symbol for thousands, as in $125K in place of $125,000.
Dollar amounts are always spelled out when they begin a sentence, so if an amount is more or less precise, to avoid a cumbersome expression such as “One hundred twenty-five thousand dollars is the starting salary,” recast the sentence so that the sentence doesn’t begin with the figure: “The starting salary is $125,000.” (Beginning a sentence with the spelled-out version is acceptable for an isolated reference in a nonfinancial context but should be avoided when using dollar figures in abundance.)
Note that hyphens are employed when a spelled-out number is part of a phrasal adjective (“The five-million-dollar budget wasn’t enough for their ambitious plans”) but not with the dollar sign and numerals (“The $5 million budget wasn’t enough for their ambitious plans”).
In international contexts, the US dollar or an equivalent amount in another currency is usually indicated as shown in this example: “The US$6.5 billion aid package was part of the deal.”
The cent sign is rarely employed, except in cases such as indication of a printed cost, as on a price tag, in which case “seventy-nine cents,” for example, would be expressed “79¢.” In financial contexts, however, use a numeral and the word cents, as in the phrase “79 cents on the dollar.”
I really, really disagree:
“In international contexts, the US dollar or an equivalent amount in another currency is usually indicated as shown in this example: “The US$6.5 billion aid package was part of the deal.”
On our planet, there are such things as DEFAULTs in qualities and quantities.
The default for “dollars” is American dollars, and for very good reasons:
1. The United States was the first COUNTRY to establish its currency in “dollars”, expressed exactly this way in English.
2. In circulation, there are FAR MORE American dollars in circulation than any other kind. Let me express this more firmly. Combine all of the other kinds of dollars in the world, count them, and multiply that by 100. This is still smaller than the number of American dollars.
3. I really mean it. As a currency in the world, all of these are minor compared with American dollars: the dollars of Australia, the Bahamas, Canada, Hong Kong, New Zealand, the West Indies, and wherever else. Anyone who does not recognize this does not know ANYTHING about statistics.
As an especially strange case, an expression like this: “The American Government spent US$200,000,000 on AIDS treatments in South Africa” is really crazy. The U.S. Government NEVER spends Australian or Canadian dollars on anything like that, and in such large amounts. I almost said never, never, but the American Embassies in Ottawa and Canberra probably have “petty cash drawers” with Canadian and Aussie dollars in them, in case someone needs to pay for a taxicab, some coffee, or a haircut.
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More defaults, including units that are obsolete now:
Pounds sterling are British (also, there is are such things as Aussie pounds or New Zealand pounds anymore, and Canada has had its own dollars ever since the 1860s!)
Francs are French, even though these are obsolete. Swiss francs are still called Swiss francs. Yen are always Japanese.
Rubles are Russian. Marks are still German, even though nobody uses them anymore. Reichmarks and whatever they used in East Germany are doubly dead.
Pesos are Mexican, by default. Pesos have been extinct in Spain for a long, long time. As an aside, there might still be Philippine pesos. In Latin America, those countries have their own units of currency, such as the bolivar in Venezuela, and except for this:
In Panama, the primary form of currency is the American dollar, and this is also true in the British Virgin Islands! (No pounds or euros there.) American dollars are quite convenient there since these are also used in Puerto Rico and the American Virgin Islands.
American dollars are widely accepted in Mexico, Canada, and the Bahamas. Now, just try to spend Australian or Hong Kong dollars in these places. You will get quizzical looks.
“Casual, isolated references….” Not so!
For example, “The last time I went to Canada, I asked if I could have a Canadian $2.00 bill. No, I could not have one, because they do not have $2.00 bills in Canada anymore. They have $2.00 coins there. I was told that they would be happy to sell me a Canadian $5.00 bill or $10.00 bill.”
Also, “On the face of the Australian $50.00 bill is a picture of the scientist Sir Howard Florey. In 1945, Flory, Fleming, and Chain won the Nobel Prize for their work in penicillin, the first antibiotic.”
Florey has been described as the greatest Australian scientist of any kind. Sir Alexander Fleming was a Scotsman who worked in London, and Sir Ernst Boris Chain was a German, and Jewish, and he left for England in 1933. He became a British citizen in 1939.
So, it was all an international effort, especially since the first large factories for making penicillin were built in the United States! Such things happened a lot during World War II.
[The US had the factories for synthetic rubber, and the huge factories for the Manhattan Project, and for nylon & dacron, and the largest shipyards, and the largest aircraft factories, and the largest steel mills. The large mills for making aluminum & magnesium were all in the US and Canada – especially because of the availability of hydroelectric power.]
“Dollar” means “American dollar” unless otherwise stated. This is a huge simplification.
Also, Jesus Christ supposedly took a Roman coin and said “Render unto Caesar what is Caesar’s, and to God what is God’s”
Now, let’s backtrack to mere words, and not gold, silver, or uranium:
“Render unto the United States the word ‘dollar’, and render unto Canada the phrase ‘Canadian dollar’, and unto Australia the phrase ‘Australian dollar’, and so forth.”