My daughter needed a calculator to check square roots last night. I couldn't believe it - we didn't have one! Well, I had my beloved HP 15C from engineering school days. RPN is cool - right?! Yeah, you can imagine how that went over. So, then I grabbed a slide rule. I know! You guessed it - worse reaction than RPN. So then I grabbed her Dell netbook, which was running Ubuntu Linux , and wrote a Perl hack that was basically
print "Enter a number\n";
$number = stdin;
$root = sqrt $number;
print "The square root of $number is $root\n";
Ha! It worked and she used it. Perl to the rescue!