With a number, "billion" can be abbreviated as b, bil[2] or bn.

The metric prefix giga indicates 1,000,000,000 times the base unit.

Its symbol is G. One billion years may be called an eon in astronomy or geology.

However, this is not common anymore, and the word has been used to mean one thousand million (1,000,000,000) for several decades.

In the Indian numbering system, it is known as 100 crore or 1 arab.