awk '
{a[NR%10]=a[NR%10]?a[NR%10]" "$0:$0}
END{a[10]=a[0];for(i=1;i<11;i++){print a[i]}}
' file

#!/usr/bin/perl
use POSIX;
sub _toArr{
	my $file=shift;
	local $/="";
	open FH,"<$file";
	my $str=<FH>;
	my @arr=split("\n",$str);
	return \@arr;
}
sub splitArr{
	my ($ref,$num)=(@_);
	my @arr=@{$ref};
	my $loop=ceil(($#arr+1)/$num);
	#print $loop,"\n";
	for(my $i=0;$i<=$loop-1;$i++){
		for(my $j=0;$j<=$num-1;$j++){
			my $tmp=$i+$loop*$j;
			print $arr[$tmp]," ";
	}
	print "\n";
	}
}
my $ref=_toArr("a.txt");
splitArr($ref,3);

line=`cat a.txt | wc -l`
nawk -v l="$line" -v col="4" '{
	num=l/col
	if(l%col!=0)
		num=int(num)+1
	arr[NR%num]=arr[NR%num]?arr[NR%num]" "$0:$0
}
END{
	arr[num]=arr[0]
	for(i=1;i<=num;i++)
		print arr[i]
}' a.txt