+**2e9** is a numerical representation denoting two billion (2,000,000,000) or 2 × 10^9, a common application of [Scientific Notation](/wiki/scientific_notation). This compact form is often employed to express incredibly large quantities, such as in [Cosmology](/wiki/cosmology) or when discussing vast data sets.
+## See also
+- [Billion](/wiki/billion)
+- [Exponent](/wiki/exponent)
+- [Large Numbers](/wiki/large_numbers)
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