One other interesting fact: A billion seconds ago, in the U.K., a
billion was defined as a million million, or 1,000,000,000,000. This officially changed in 1974, when the government adopted the
short scale large number naming system, redefining a
billion to mean a thousand million, or 1,000,000,000.
Most English-speaking countries now use the short scale billion, like the US does, while many non-English-speaking countries use the long scale system, which defines
billion as a million million.
Wikipedia: BillionWikipedia: Long and short scales