Spell out numbers zero through nine in text. Use numerals for numbers 10 and higher. For amounts in the millions, billions and trillions, use a figure-word combination: 1 million people, $2 billion. For large numbers, do not use more than two numerals beyond the decimimal point. $1.7 million, 3.75 million people. Use .5 to indicate a half: 1.5 million, not 1 1/2 million.
Phone numbers should use hyphens between the first set of numbers and the second set of numbers. No parentheses. Example: 210-567-7000. The lowercase letter “x” is acceptable for extensions. Example: 210-567-7000 x0000.