Accounting only for integers, we have: 
my $n = 0;
$n += map .5*(1+length)*length, $s =~ /\d+/g;

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This makes use of the triangular pattern that the number "1234" has 10 "embedded numbers" (1234, 123, 12, 1, 234, 23, 2, 34, 3, 4). No need to put all that hard work in the regex itself. Although, if you wanted to, it'd be: 
our $n;
$s =~ /\d+(??{ ++$n })(?!)/;

[download]
_____________________________________________________
Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart

In reply to Re^3: number of numbers in a string by japhy
in thread number of numbers in a string by concept03

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