Although a scalar is either a number or a string, it's useful to look at numbers and strings separately for the moment. Numbers first, strings in a minute... .
 Or a reference, but that's an advanced topic.
As you'll see in the next few paragraphs, you can specify both integers (whole numbers, like 17 or 342) and floating-point numbers (real numbers with decimal points, like 3.14, or 1.35 times 1025). But internally, Perl computes only with double-precision floating-point values. This means that there are no integer values internal to Perl; an integer constant in the program is treated as the equivalent floating-point value. You probably won't notice the conversion (or care much), but you should stop looking for integer operations (as opposed to floating-point operations), because there aren't any.
 A "double-precision floating-point value" is whatever the C compiler that compiled Perl used for a double declaration.
 Unless you use "integer mode," but that's not on by default.
A literal is the way a value is represented in the text of the Perl program. You could also call this a constant in your program, but we'll use the term literal. Literals are the way data is represented in the source code of your program as input to the Perl compiler. (Data that is read from or written to files is treated similarly, but not identically.)
Perl accepts the complete set of floating-point literals ...