$ perl -e'printf "%.100g\n", $ARGV[0]' 0.1
0.1000000000000000055511151231257827021181583404541015625

$ perl -e'printf "%.100g\n", $ARGV[0]' 0.8
0.8000000000000000444089209850062616169452667236328125

$ perl -e'printf "%.100g\n", $ARGV[0]' 0.01
0.01000000000000000020816681711721685132943093776702880859375