#!/usr/bin/perl

# https://perlmonks.org/?node_id=1226526

use strict;
use warnings;

while(1)
  {
  my $input;
  my $random_integer1 = int rand 100;
  my $random_integer2 = int rand 100;
  do
    {
    print "What is $random_integer1 - $random_integer2 = ";
    chomp( $input = <STDIN> );
    }
  while $input != $random_integer1 - $random_integer2 and
      print "Sorry you're wrong, have another go.\n\n";
  print "Well done.! you are correct.\n\n";
  }