[chris@pineapple ranges-892828]$ perl ranges -M=9999997 -N=1
 0 : from       0 to 9999997 (9999998)
[chris@pineapple ranges-892828]$ perl ranges -M=9999997 -N=2
 0 : from       0 to 4999998 (4999999)
 1 : from 4999999 to 9999997 (4999999)
[chris@pineapple ranges-892828]$ perl ranges -M=9999997 -N=3
 0 : from       0 to 3333331 (3333332)
 1 : from 3333332 to 6666664 (3333333)
 2 : from 6666665 to 9999997 (3333333)
[chris@pineapple ranges-892828]$ perl ranges -M=9999997 -N=4
 0 : from       0 to 2499998 (2499999)
 1 : from 2499999 to 4999998 (2500000)
 2 : from 4999999 to 7499997 (2499999)
 3 : from 7499998 to 9999997 (2500000)
[chris@pineapple ranges-892828]$ perl ranges -M=9999997 -N=5
 0 : from       0 to 1999998 (1999999)
 1 : from 1999999 to 3999998 (2000000)
 2 : from 3999999 to 5999997 (1999999)
 3 : from 5999998 to 7999997 (2000000)
 4 : from 7999998 to 9999997 (2000000)
[chris@pineapple ranges-892828]$ perl ranges -M=9999997 -N=6
 0 : from       0 to 1666665 (1666666)
 1 : from 1666666 to 3333331 (1666666)
 2 : from 3333332 to 4999998 (1666667)
 3 : from 4999999 to 6666664 (1666666)
 4 : from 6666665 to 8333330 (1666666)
 5 : from 8333331 to 9999997 (1666667)
[chris@pineapple ranges-892828]$ perl ranges -M=9999997 -N=7
 0 : from       0 to 1428570 (1428571)
 1 : from 1428571 to 2857141 (1428571)
 2 : from 2857142 to 4285712 (1428571)
 3 : from 4285713 to 5714283 (1428571)
 4 : from 5714284 to 7142854 (1428571)
 5 : from 7142855 to 8571425 (1428571)
 6 : from 8571426 to 9999997 (1428572)
[chris@pineapple ranges-892828]$ perl ranges -M=9999997 -N=8
 0 : from       0 to 1249998 (1249999)
 1 : from 1249999 to 2499998 (1250000)
 2 : from 2499999 to 3749998 (1250000)
 3 : from 3749999 to 4999998 (1250000)
 4 : from 4999999 to 6249997 (1249999)
 5 : from 6249998 to 7499997 (1250000)
 6 : from 7499998 to 8749997 (1250000)
 7 : from 8749998 to 9999997 (1250000)
[chris@pineapple ranges-892828]$ perl ranges -M=9999997 -N=9
 0 : from       0 to 1111109 (1111110)
 1 : from 1111110 to 2222220 (1111111)
 2 : from 2222221 to 3333331 (1111111)
 3 : from 3333332 to 4444442 (1111111)
 4 : from 4444443 to 5555553 (1111111)
 5 : from 5555554 to 6666664 (1111111)
 6 : from 6666665 to 7777775 (1111111)
 7 : from 7777776 to 8888886 (1111111)
 8 : from 8888887 to 9999997 (1111111)

##</code><code>##

[chris@pineapple ranges-892828]$ perl ranges -M=9 -N=1
 0 : from       0 to       9 (     10)
[chris@pineapple ranges-892828]$ perl ranges -M=9 -N=2
 0 : from       0 to       4 (      5)
 1 : from       5 to       9 (      5)
[chris@pineapple ranges-892828]$ perl ranges -M=9 -N=3
 0 : from       0 to       2 (      3)
 1 : from       3 to       5 (      3)
 2 : from       6 to       9 (      4)
[chris@pineapple ranges-892828]$ perl ranges -M=9 -N=4
 0 : from       0 to       1 (      2)
 1 : from       2 to       4 (      3)
 2 : from       5 to       6 (      2)
 3 : from       7 to       9 (      3)
[chris@pineapple ranges-892828]$ perl ranges -M=9 -N=5
 0 : from       0 to       1 (      2)
 1 : from       2 to       3 (      2)
 2 : from       4 to       5 (      2)
 3 : from       6 to       7 (      2)
 4 : from       8 to       9 (      2)
[chris@pineapple ranges-892828]$ perl ranges -M=9 -N=6
 0 : from       0 to       0 (      1)
 1 : from       1 to       2 (      2)
 2 : from       3 to       4 (      2)
 3 : from       5 to       5 (      1)
 4 : from       6 to       7 (      2)
 5 : from       8 to       9 (      2)
[chris@pineapple ranges-892828]$ perl ranges -M=4 -N=0
N < 1 makes no sense.

[chris@pineapple ranges-892828]$ perl ranges -M=4 -N=1
 0 : from       0 to       4 (      5)
[chris@pineapple ranges-892828]$ perl ranges -M=4 -N=2
 0 : from       0 to       1 (      2)
 1 : from       2 to       4 (      3)
[chris@pineapple ranges-892828]$ perl ranges -M=4 -N=3
 0 : from       0 to       0 (      1)
 1 : from       1 to       2 (      2)
 2 : from       3 to       4 (      2)
[chris@pineapple ranges-892828]$ perl ranges -M=4 -N=4
 0 : from       0 to       0 (      1)
 1 : from       1 to       1 (      1)
 2 : from       2 to       2 (      1)
 3 : from       3 to       4 (      2)
[chris@pineapple ranges-892828]$ perl ranges -M=4 -N=5
M must be equal to N or larger than N.

##</code><code>##

#! perl -slw
use strict;

our $N //= 2;
our $M //= 1e6;

die "N < 1 makes no sense.\n\n" if $N < 1;
die "M must be equal to N or larger than N.\n\n" if $M < $N;

my $size = ( $M + 1 ) / $N;

my @ranges;
for ( my $i = 0; $i < $M; $i += $size ) {
    my ( $j, $k ) = ( int $i, int ($i + $size) );
    push @ranges, [ $j, $k - 1, $k - $j  ];
}

( printf "%2d : from %7d to %7d (%7d)\n",
        $_,
        @{ $ranges[ $_ ] }
) for 0 .. $#ranges;

__END__