See hex.

>perl -wMstrict -le
"my $i = 100;
 my $x = hex $i;
 print $x;
 printf qq{0x%x \n}, $x;
 ;;
 $i = '200';
 $x = hex $i;
 print $x;
 printf qq{0x%x \n}, $x;
"
256
0x100
512
0x200
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