use strict; $n = 1000; $\=$/;
print $n +4;  # indirect object notation, + is sign marking 4 as positive (unary plus)
print $n + 4; # $n + 4 is addition, result is printed
print +$n +4; # unary + prevents $n from being interpreted as file handle, 1004 is printed
print ($n +4); # same as case 1
print ($n + 4); # same as case 2
print+($n +4); #same as case 3