MONEY
Spell out one through nine and the expressions a hundred, a thousand, a million, a billion; otherwise use figures:
five dollars, $20, $35, a hundred dollars, a $90 loan, $110, $6,000, $340,000
If a number is spelled out, also spell out dollar; if a figure is used, then use the dollar symbol:
a bill for three million dollars, $20 billion, a bill for $33 million
The words million and billion are preferably spelled out:
$800 million, more than $30 billion, one million dollars.
Use figures for all numbers that contain decimals:
an $8.5 billion deficit
Hyphenate compound modifiers that include a spelled-out word:
a two-dollar tie, but a $45 shirt.
Don't use hyphens in a simple compound modifier:
a $40 million dam.
Use a hyphen in longer compound modifier:
a $20 million-a-year plan.
Use an apostrophe in such expressions as 20 dollars' worth, a million dollars' worth.
Small sums: eight cents, 15 cents; not 15¢ or $0.15.
Amounts in dollars and cents: $2.98, $6.25, $625.40.
In general, spell out units of foreign currency and do not italicize them:
two pounds 60 pence; 53 pesos, 74 euros.
Give the nearest rounded U.S. equivalent at least once within parentheses:
It cost a hundred kroner ($20), four francs (80 cents).
When conversions are given for sums of money employing the same unit of currency, generally follow these examples:
in Canada the current quotation was $2.69 (U.S. $2.47) a box
the New Zealand dollar is worth around 55 U.S. cents
a $325 million (U.S.) resort development
In British currency the pound (£) symbol may be used as one would use the dollar symbol. Note that the term billion differs in the U.S. and British systems.
When comparing amounts of money from different time periods, it may be helpful to adjust the figures so they are comparable: use terms such as constant dollars, adjusted for inflation, or in today's dollars to indicate an adjustment.