Whether a number or a string is needed

[zz19]

Perl automatically converts between numbers to strings as needed. How does it know whether a number or a string is needed?

[zufit]

It all depends upon the operator being used on the scalar value. If an operator expects a number (like + does), Perl will see the value as a number. If an operator expects a string (like . does), Perl will see the value as a string. So you don't need to worry about the difference between numbers and strings, just use the proper operators, and Perl will make it all work.