1E45

1E45 is a numeric value written in scientific notation, representing the decimal number 1 × 10^45. In this form, the letter E (or e) indicates an exponent of base 10, so 1E45 equals 10 raised to the 45th power. The notation is widely used in science, engineering, and computing to express very large (or very small) quantities without writing long strings of zeros, and it is case-insensitive in most contexts because many languages treat 'E' and 'e' the same.

In programming and data formats, 1E45 can be written as 1e45 as a floating-point literal. It is representable in standard double-precision floating point (IEEE 754) but would overflow a 32-bit float. As a reference scale, 10^45 is far larger than many common counts (for example, the estimated number of atoms in the observable universe is around 10^80, which is orders of magnitude higher than 10^45), though 10^45 is still a useful magnitude in fields like cosmology, high-energy physics, and large-scale simulations for setting parameters or carrying out order-of-magnitude estimates.

Note that 1E45 is distinct from 1E-45, which denotes a very small quantity equal to 10^-45.

See also scientific notation, floating-point arithmetic, exponential notation.