Numbers should be spelled out as a word from “one” up to and including “nine’. For “10” and beyond that they should appear as numerals.
Use a comma to separate large numbers into groups of three numerals, as in “1,000” and “100,000”. This can help avoid confusion with years and street numbers, which do not use commas. (Style guides vary on this point with AAP agreeing with the above, Fairfax and News Ltd prefer to omit the comma in all four digit numbers.)
Million should be spelled out. Note that it is “two million” with “two” as a word, and “12 million” with “12” or any other amount greater than “nine” as a numeral.
In broadcast write out all numbers in words as you would say them, as in “two hundred and fifty people gathered” not “250 people gathered”. In TV use a graphic to help with detailed numbers.
If the exact number is not crucial to the story then you can round it off. It is better to say “nearly half a million people” rather than “four hundred and eighty-nine thousand people”. Where the exact number is relevant then give the exact figure, as in “Queensland’s unemployment rate has risen to 10 point three per cent”
Be careful with sentences starting with numbers greater than “nine”, as numerals should not be used to start sentences. Try rephrasing the sentence. If this is not practical, spell the number out, as in “Two hundred people”.
It helps to announce a telephone number twice in broadcast.