c:\test>572961 9991230061 9991230061 is not found 9991230062 9991230062 is found 9991230063 9991230063 is not found Terminating on signal SIGINT(2) c:\test>perl -wle"printf qq[%03d%03d%04d\n], int( rand 1000 ), int( rand 1000 ), int( rand 10000 ) for 1 .. 1e3" | perl 572961.pl >nul File for area code '000' not found at 572961.pl line 12, line 57. 999 trials of lookup (32.287s total), 32.319ms/trial