1e9

1e9 is the scientific notation for the number 1 × 10^9. In decimal form, this equals 1,000,000,000, commonly referred to as one billion in the short scale.

A common use of the notation is in computing and programming, where 1e9 is written as a literal representing a floating-point value approximately equal to one billion. In many languages, such as Python and JavaScript, 1e9 evaluates to a floating-point number equal to 1000000000.0 or 1000000000, respectively. In languages like C or Java, 1e9 is typically a double-precision floating constant; integer literals of this magnitude are written without the exponent.

Applications include representing large counts, data sizes, and thresholds, for example 1e9 bytes roughly equaling one gigabyte in decimal terms. Distinctions between decimal gigabytes (10^9 bytes) and gibibytes (2^30 bytes, about 1.074 × 10^9) are common in storage and memory contexts, which can cause confusion.

Floating-point considerations: 1e9 is within the range where IEEE 754 double-precision numbers can store the value exactly, since it is less than 2^53. Nevertheless, using 1e9 for exact integers in code may rely on the language’s numeric type; for exact integers, explicit integer literals are preferred.