When a string is enclosed in double quotes, scalar variables and arrays are interpolated.
#Hashes are not interpolated within the string enclosed in double quotes.
#string literals (e.g., \t, \n) must be enclosed in double quotes for backslash interpretation.
#A single quote may be enclosed in double quotes, as in "I don't care!"
# Double quotes
$num=5;
print "The number is $num.\n";
print "I need \$5.00.\n";
print "\t\tI can't help you.\n";