The notation with the e
is a numeric literal, part of the lexical syntax of many programming languages, based on standard form/scientific notation.
The purpose of this notation is to allow you to specify very large/small numbers by shifting the point position. It's not intended to allow you to encode multiplication by some arbitrary power of 10 into numeric literals. Therefore, that point and the following digits aren't even recognised as part of the numeric literal token.
If you want arbitrary powers, as you've found, there are math functions and operators that do the job. Unlike a numeric literal, you even get to determine the parameter values at run-time.