From Modern Perl book:

The internal data structure which represents a scalar in Perl 5 has a numeric slot and a string slot.

The dualvar() function within the core Scalar::Util module allows you to manipulate both values directly within a single scalar. Similarly, the module’s looks_like_number() function returns true if the scalar value provided is something Perl 5 would interpret as a number.

perl -MData::Dumper -E "say for Dumper([ 1, '1' ]),eval qq(1+'1'), len
+gth qq(1....).1;"
$VAR1 = [
          1,
          '1'
        ];

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