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+#!/usr/bin/env perl
+#
+# Create a script that prints nth order forward difference series. You should be
+# a able to pass the list of numbers and order number as command line
+# parameters. Let me show you with an example.
+#
+# Suppose we have list (X) of numbers: 5, 9, 2, 8, 1, 6 and we would like to
+# create 1st order forward difference series (Y). So using the formula Y(i) =
+# X(i+1) - X(i), we get the following numbers: (9-5), (2-9), (8-2), (1-8),
+# (6-1). In short, the final series would be: 4, -7, 6, -7, 5. If you noticed,
+# it has one less number than the original series. Similary you can carry on 2nd
+# order forward difference series like: (-7-4), (6+7), (-7-6), (5+7) => -11, 13,
+# -13, 12.
+################################################################################
+
+use strict;
+use warnings;
+
+@ARGV == 2 or die "Usage: $0 <order> <x1,x2,...xn>";
+my $order = shift;
+my @xs = split ',', shift;
+
+foreach (1 .. $order) {
+    foreach my $i (0 .. $#xs-1) {
+        $xs[$i] = $xs[$i+1] - $xs[$i];
+    }
+    pop @xs;
+}
+
+print "@xs\n";