What am I missing?

2 things. First, you can't have multiple matches (//g) AND have your regex anchored at the start of the string.

Second, the //g will return all the captured matches, so you don't need that last +. In fact, you can't HAVE that last +, or it doesn't work.

my @lines = ("a 1 2",
         "b 3 4 5 6",
         "c 7 8 9");

foreach (@lines) {
    # you can't match multiple times starting at ^!
    my @list = m/(\s+\d+)/g; # no last +
    print @list, "\n";
  }
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Of course, demerphq made a very good point about that regex not being sufficient to match all numbers...
--
Mike