C:\test>\perl5.18\perl\bin\perl.exe -le"printf qq[%f : %f\n], $_ % 10, ( $_ / 10 ) for 9_000_000_000_000_000_011, 10_000_000_000_000_000_011" 1.000000 : 900000000000000000.000000 1.000000 : 1000000000000000000.000000 #### C:\test>\perl5.18\perl\bin\perl.exe -Minteger -le"printf qq[%u : %u\n], $_ % 10, ( $_ / 10 ) for 9_000_000_000_000_000_011, 10_000_000_000_000_000_011" 1 : 900000000000000001 18446744073709551611 : 17602069666338596456 C:\test>\perl5.18\perl\bin\perl.exe -Minteger -le"printf qq[%d : %d\n], $_ % 10, ( $_ / 10 ) for 9_000_000_000_000_000_011, 10_000_000_000_000_000_011" 1 : 900000000000000001 -5 : -844674407370955160