+**13e9** represents the number 13 billion (13,000,000,000), expressed using [scientific notation](/wiki/Scientific_Notation). This vast [scale](/wiki/Scale) is often referenced when discussing immense quantities, such as the estimated age of the universe or significant population data.
+## See also
+- [Orders of Magnitude](/wiki/Orders_of_Magnitude)
+- [Large Numbers](/wiki/Large_Numbers)
+- [Cosmology](/wiki/Cosmology)
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