sub multiply_by {
  my $multiplier = $_[0];
  return sub {
    return $_[0] * $multiplier;
  }
}

my $times2 = multiply_by(2);
my $times10 = multiply_by(10);

print &$times2(4), "\n";
print &$times2(6), "\n";
print &$times10(4) ,"\n";

# Results:
# 8
# 12
# 40