DB<220>  for (0..20) {$e=2**$_; $x = 1000 * ( $e + 4/25 ); printf "$_:$e => %.20f\n", $x if ($x-int($x))} 
5:32 => 32159.99999999999636202119
8:256 => 256160.00000000002910383046
9:512 => 512159.99999999994179233909
10:1024 => 1024160.00000000011641532183
11:2048 => 2048159.99999999976716935635
15:32768 => 32768160.00000000372529029846
18:262144 => 262144159.99999997019767761230
19:524288 => 524288160.00000005960464477539
20:1048576 => 1048576159.99999988079071044922