Be sure to re-read an edition of your target publication and check how it uses numbers, because there are no absolute rules on numbers. But in mainstream journalism in Australia, these are the general guidelines:
One to nine are written as words: one, two, three, four, five, six, seven, eight, nine.
The number 10 and all numbers thereafter are written as numerals, that is 10, 11, 12, 999 . . .
If you start a sentence with a number you are supposed to express that number in words (without commas) and not in numerals, such as: “Eleven thousand five hundred and twenty-two wild animals were counted by her.” This takes space and looks peculiar, even if it is correct. So most editors prefer the sentence to be written in such a way that the number is not used first, such as: “She counted 11,522 wild animals.” If it’s a short number you could write: “Twelve dogs barked.”
Also when writing numbers in the thousands or millions, keep in mind that the mainstream journalistic style is to use commas, such as 12,000 and 17,000,000 not 12 000 or 17 000 000.
But if writing the thousand numbers 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000 or 9000 write them without a comma or a space. But if writing a number that is not a thousand number, like say 6,702 write it with a comma to make it easier to read.
Make sure you know these:
1 million is 1000 thousands (1,000,000)
1 billion is 1000 millions (1,000,000,000)
1 trillion is 1 million million (1,000,000,000,000)
I doubt that in your lifetime you’ll ever write a story needing the number in the quadrillions. One quadrillion is (in the US and increasingly in general use in English) a million times a billion, or 1 followed by 15 zeroes. You may need it in stories about DNA where huge numbers are needed.
Numbers in the millions, billions and trillions are written partly in numerals, partly in words:
Use a space between the numerals and the word.
In the decimal system a kilo is a thousand, mega is a million and giga is a billion. But just to confuse you, in the binary system that computers use, a kilo is 1,024. Thus a 300GB (300 giga-byte) hard drive has 300 billion bytes capacity but registers as 279GB on Windows . . . don’t worry about it. You’re unlikely to use it unless writing for highly-technical computer magazines.
Money amounts are written as $4 not $4.00 and not four dollars. If you use Australian dollars and another nation’s currency in the same article, identify them as say US$4,000 and AU$8,000. If you write 23 million yen or ¥23 million be sure to convert this to Australian dollars so your readers understand the size of the amount. You must convert money figures so Australians understand values.
It’s no use telling your readers that something costs eight pounds or 2000 yen or 40 roubles or 100 euros, unless you convert it to Australian dollars. And use the WORDS for foreign currency not the signs, like £ for English pounds or ¥ for Japanese yen. So, write like this: In Tokyo a Big Mac costs 70 yen (A$3.50), while in London it costs four pounds (A$2.25). My conversions are not accurate but your conversions must be. Double check, please. For a free, up-to-the-minute, easy-to-use currency converter, log on to www.xe.com and use your calculator.
Don’t write four-and-a-half or worse 4-1/2, but write 4½ (and no space between the 4 and the ½). For fractions go to “Insert” on your toolbar, then “Symbol”. Find your fraction and “insert” it and “close”, and go back to your document.
Also use your “Insert” button if using the ¢ symbol instead of writing cents or typing a plain c for cents.
Times of the day are NOT written as 9:15 a.m. or two-thirty or (rarely ever) 6 o’clock. It’s 9.15am (using a fullstop between 9 and 15 but not fullstops after the a and the m and no spaces. It’s 2.30am or 2.30pm. And usually it’s 6am or 6pm rather than 6 o’clock.
NEVER write 12am or 12pm. There is no general agreement or understanding of whether noon is 12am or 12pm, and whether midnight is 12am or 12pm. Always write 12 noon or 12 midnight.
Periods of time are written as the 1800s, not the 1800’s. Or the 70s, not the 70’s. And while it’s say 3000BC (Before Christ) with the BC after the number, it’s AD2008 with the AD before the number (AD = anno Domini, Latin for “in the year of our Lord”).
Most publications prefer 92% to 92 per cent or 92 percent. Any fraction of a percentage should be written as 92.25%, not 92¼%.
Why all these odd guidelines?
Well, I’ve never heard good reasons why, but these ARE the usual customs in mainstream journalism.