Unfortunately, the expression billion is ambiguous, outside the US, and regions of US-influenced language.  Its generally understood to be one thousand millions in the US, but some UK folk, and much of the rest of the world will understand it to be one million millions. There's a good explanation of Long and short scales and why its better to avoid using terms like billion when writing for general audiences. I'm not going to revert the edit, but I'd vote to leave it as "thousand million" and not "billion".   

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