Perl will automatically do the right thing with a scalar depending on the context in which you use it. If you were to say:

my $x = "1";
my $y = "2";
print $x + $y, "\n";
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you'll get 3. If you say:

my $x = "1";
my $y = "2";
print $x . $y, "\n";
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you'll get 12 ("2" appended to "1"). To force interpretation in a numeric context, you can try:

my $x = "10abc";
print $x + 0, "\n";
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and you'll get 10. Note that this only works on scalars starting with digits. Strip them out with a regex if you need to.