Billionth


One billionth is the reciprocal of a billion, which means it has one of two definitions depending on whether the long scale or short scale definition is being used.

Short scale

In the short scale, a billionth is equal to 0.000 000 001, or 1 x 10−9 in scientific notation or standard form. The prefix for this number is nano, and is abbreviated as "n".

Long scale

In the long scale, a billionth is equal to 0.000 000 000 001, or 1 x 10−12 in scientific notation or standard form. The prefix for this number is pico-, and is abbreviated as "p".