Billion

From Wiki4CAM

A billion can have two different meanings. In the United States, it is the number 1,000,000,000 - a thousand million.

In Commonwealth usage, as well as in most non-English languages, it is the number 1,000,000,000,000 - a million million, while a thousand million is called a milliard.

It is generally wise to use scientific notation to eliminate any any ambiguity: 10⁹ or 10¹² leaves no doubt as to which number is meant.