perl -e '
for $j (1000,1_000_000,1_000_000_000) {
$i=$j**2;
print "\n",$j,": \t",$i,"\t= ";
printf "%020.0f", $i;
}'

1000: 	1000000	= 00000000000001000000
1000000: 	1000000000000	= 00000001000000000000
1000000000: 	1e+18	= 01000000000000000000