Maybe: 
my $problem = qr{
  (\d+
   \s+
   [\+|\-|\*|\/]
   \s+
   \d+)
}x;

my $evaluation = '10 / 2';

{
  local $_ = $evaluation;
  s/$problem/$1/ee;
  print
}

[download]
STDOUT: 5


In reply to Re: '+' to + by sh1tn
in thread '+' to + by NateTut

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