In science, en can refer to the prefix en- (Greek) meaning "in" or "within" or or alternatively "to go into" or "cause to be", depending, as in en-ergon (work), en-tropy (entropy), or en-ergy (energy); or the abbreviation EN (technical) maning exponent E to the power of some number N.

Exponent
The term EN is sometimes found as an old-fashioned short notation scheme for exponent E to the power of some number N, which is written formulaically as follows:

$\text{EN} = 10^N \,$

where N is a positive number. If N equals 22, for example:

$\text{E22} = 10^{22} \,$

This notation scheme is useful in expressing shorthand notation for numbers of atoms in a human molecule which can reach upwards E27, depending on atom, such as hydrogen or oxygen. Hence, for instance, the notation:

$Zn_{10,000,000,000,000,000,000,000} \,$

become shortened to:

ZnE22

or in subscript notation:

$Z_{E22} \,$

or in Latex notation:

$Z_{10^{22}} \,$

all of which are equivalent, which signify that there are 10 sextillion Zinc atoms in the average human molecule.