$fp2 =  -8.2727285363069939e-293;;
printf "% 25.17g\n", $fp2;;
 -7.9999999999999948e-293     ### WTF? ###

##</code><code>##

C:\>perl -le "printf '%.16e', -8.2727285363069939e-293;"
-7.9999999999999948e-293

##</code><code>##

C:\>perl -le "print scalar reverse unpack 'h*', pack 'd<', -7.9999999999999948e-293;"
83465a792c83e3b6

C:\>perl -le "print scalar reverse unpack 'h*', pack 'd<', -8.2727285363069939e-293;"
83498bf832dfdfab