1E

1e is a notation used in decimal scientific notation to represent numbers of the form 1 × 10^n, where the letter 'e' stands for exponent. In this usage, the exponent is written after the letter, optionally preceded by a plus or minus sign. For example, 1e3 equals 1000, and 1e-4 equals 0.0001. The 'e' here is not the mathematical constant e, but a shorthand for the exponent base of 10.

In programming languages and data formats, 1e is commonly used as a floating-point literal. The notation can be written as 1e6 or 1E6, with both lowercase and uppercase 'e' accepted in many languages. The mantissa can be any valid decimal number, not only 1 (e.g., 3.14e2 equals 314). This form is widely used to express very large or very small numbers concisely.

In broader scientific and technical contexts, scientific notation facilitates reading and writing numbers, especially in fields like physics, chemistry, and engineering. It appears in calculators, spreadsheets, and data files, including JSON and CSV, as a compact representation of numbers such as 4.5e-7.

Caveats include not confusing this usage with the mathematical constant e. In 1e notation, the base is 10, and the exponent follows the 'e' symbol. The symbol does not denote a unit by itself; its meaning is to indicate the power of ten applied to the leading significand.