# $n%2 will be 1 if $n is odd and 0 if $n is even.
my $n=scalar(@aSomeNumbers);
my ($n1, $n2);
if ($n%2) {
   #if $n is even it is safe to divide by 2
   $n1=$n2=$n/2;
} else {
   #add one so we get an even number again and can divide safely by 2
   $n1=($n+1)/2;
   $n2=$n-$n1;
}