One billion in numerals is written as 1,000,000,000. To write one billion in numerals, you will need ten figures before the decimal point. For example, seven billion translates to 7,000,000,000.
In scientific notation, a billion is any number to the power of nine: 1 x 10^{9}
A billion is equivalent to a thousand million, which explains the need for nine zeros. The value of a billion was once a subject of debate among the English and the French. The English believed a billion to be any number to the power of 12, while the French thought the power of 12 too impractical and based the billion on the power of nine. The power of nine has since become the most accepted form of the billion.
1,000,000,000.
http://wiki.answers.com/Q/How_do_you_write_1_billi...

1. Write the number representing 1 billion. One billion is one thousand million, or 1,000,000,000 in the U.S. system. That's a 1 followed by nine zeros. 2. Change any one of the zeros
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1280000000000. Thanks for using ChaCha!
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3.8 billion, written out, is 3,800,000,000 or 3800000000 without the commas.
http://wiki.answers.com/Q/How_do_you_write_3.8_bil...
