#!/usr/bin/perl

use strict;
use Data::Dumper;

my %number = ( 23 => [ qq[g1,23,24], qq[g2,34,35] ],
               24 => [ qq[g3,45,56], qq[g4,36,48] ]
             );

$number{25}->[0] = qq[g5,55,56];

print Dumper \%number;