billion, B (billion)

In North American usage, the word billion means a thousand million (10⁹); but in British usage, it means a million million (10¹²). The use of figures avoids all ambiguity.

• Genna won $2,000,000 with Lotto 649 and not $2,000,000,000 as reported in the local press.

Where billion is qualified or preceded immediately by a number, do not use the plural form billions.

• The new bridge cost over $4 billion to build.
• There are now more than six billion people living on our planet.

BUT

• There are billions and billions of stars in the sky.
• Hundreds of billions of dollars were spent in preparation for the millennium bug.

Also, the abbreviation B for billion—found in newspapers especially—should not be used in formal writing. Note that there is no space between the number and the letter (e.g. 5B), whereas there is a space between the number and the word.

• Informal: Federal aid was reduced by $2.3B in the budget.
• Formal: Federal aid was reduced by $2.3 billion in the budget.