Not sure that what bugs you was what bugged me, but... 

#!/usr/bin/perl

use strict;
use warnings;

# Faked input
my $N = 5;
my $M = 9999997;

# Compute the sizes of the ranges
$M += 1;
my $step = int $M / $N;
my $extra = $M - $N * $step;
my(@sizes) = ($step) x $N;
@sizes = map { ($extra-- > 0) ? $_ + 1 : $_ } @sizes;

# Generate the ranges
my @ranges = ([undef, -1]);
for my $size (@sizes) {
  my $m = $ranges[-1][1];
  push( @ranges, [ $m + 1, $m + $size ] );
}
shift @ranges;

# Output
printf "%2d : from %7d to %7d (%7d)\n",
    $_, @{ $ranges[ $_ ] },
    $ranges[ $_ ][ 1 ] - $ranges[ $_ ][ 0 ] + 1
    for 0 .. $#ranges;

[download]

This produces: 

 0 : from       0 to 1999999 (2000000)
 1 : from 2000000 to 3999999 (2000000)
 2 : from 4000000 to 5999999 (2000000)
 3 : from 6000000 to 7999998 (1999999)
 4 : from 7999999 to 9999997 (1999999)

[download]

In reply to Re: Split range 0 to M into N non-overlapping (roughly equal) ranges. by eye
in thread Split range 0 to M into N non-overlapping (roughly equal) ranges. by BrowserUk

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